Will they remain cool games if Game Pass doesn't take off and make back the $70 billion quickly, along with enough profits to keep the beast fed?

MS is paying for this acquisition so they will have made the money they spent on the acquisition by the time it goes through. They would also rather invest in something than let the money sit and do nothing. Why does Game Pass need to make the money back quickly? They are clearly playing the long game. It could take 15+ years and they are likely cool with it. 

MS had that $70 billion cash in their pockets, so no, they didn't need to make that money to make the purchase.

Unless XB exists just to be a subsidy for MS, making money back slowly is bad business for someone in MS's position.

If MS were fine with outrageous XB subsidies and didn't care how long the payback took, why have they waited 20 years to go big now?

Simplest answer to me is that they aren't planning on taking forever to pay it off. How that plays out will be the interesting part for XB owners.

I don't think many saw the XB Series S coming, the console shortages, the much more positive MS PR and more negative Sony PR, etc.

There's so many variables that assuming it's just going to succeed because it's MS or a Netflix like product, isn't looking broad enough. That's not saying Game Pass can't succeed, because it could, but it's sure taking it's sweet time to get there. If AB doesn't increase the momentum considerably, then MS has their work cut out for them, and then some.

Its called new management.  New CEO, new head of xbox, new direction for MS as a company with subscription services. MS as a business has changed in those 20 years.  Yes, GP is not a plan for making huge money today as MS has been careful to taking their time building the infrastructure to support it from spending billions on server farms and their cloud infrastructure all over the world to adding pieces to GP as the system continue to grow and building their first party content.  A company as large as MS does not have to make back a purchase right away.  I have worked for multiple companies who has either purchase or been purchase by another company and no it's not always about making your money back its about market position and expanding the capability of your company in a competitive environment.  MS purchasing publishers are not about making back their purchase in cash, it's about growth of their entertainment division and that is currently the position they are in a growth cycle for entertainment.

The paying it off is the simplest part of this whole story, since both publishers are all in the green.  It's not like they are purchasing companies in the red who products do not sell.  The larger scope is they expect more subs. More subs then just a console lifecycle can bring but global subs that allows gamers on whatever platform they chose play MS games.  PC, console, mobile, TV, Dongle you name it and MS wants to be there.  It's a pretty simple strategy that does not need a lot of thought, but it does need a lot of money and time building and setting all the blocks in place to achieve.

So the answer to the OP is they're right then. After 20 years, these $70 billion acquisitions are going towards helping non XB owners.

Errr.. I was not trying to compliment anything. I was just pointing out that regardless of how the OP (or you) feel about these games, these fear that Microsoft will, all of a sudden, stop caring about new IPs is... unfunded.

And sorry, but before it was completely impossible to compare Microsoft and Sony's games performance because they had never competed on the same platform, so it was easy to get away with claims like "Microsoft hasn't been making new IP at the same level as Sony"; but now WE DO have them competing in a totally neutral ground, and as you can see, Sea of Thieves makes a great argument as one of the most successful new IPs of the last generation.

Spider-Man is a new IP? There have been Spider-Man games since 1978, on PlayStation since 2000:
https://www.mobygames.com/game-group/spider-man-licensees/offset,75/so,1d/

God of War is a new IP? There have been GoW games since 2005.

Pikmin is a new IP? There have been Pikmin games since 2001.

Games get put on GamePass.

Games get bigger budgets.

Games are blocked from the gargantuan amounts of Sony moneyhats.

There’s three benefits for Xbox users right there off the top of my head ?

Spider-Man isn't a new IP but it's a wholly new telling of the tale, not taking forward from any other iteration ever put to games. That's just sort of how comic book stuff works. I considered Batman Arkham series to be a new IP in that it's that particular take on the adaptation. Same as the Spider-Man ones from Insomniac. IT's its own canon and such. 

God of war is similar, in that it's basically a new genre compared to the old games. Soulslike action RPG instead of Hack and Slash. Not new, but the point was that Sony is willing to try new things a lot more, to try risking things more than before. To change things up for the better. 

Pikmin isn't new at all but it did come after Nintendo's established IP bombing of the late 80s/early 90s, and alongside Splatoon and ARMs shows that Nintendo does occasionally make new IPs. As an extension of that, Nintendo also tries new things with each franchise entry. Like God of War, you can see just how different that Breath of the Wild is compared to Skyward Sword or even Twilight Princess. 

The point wasn't that they exclusively make new IP, but that these companies mix things up a bit by trying new things. Sony COULD just release a new Ratchet & Clank game every year, but they don't. They could just keep releasing Uncharted games, but they don't. A lot of their teams make new IP, have some fun with them, they do reasonably well, and they move on or try something new. inFamous, Resistance, Sly Cooper, Jak and Daxter, and Killzone are examples of IP that could have been ongoing stories that never ended but the devs/Sony were willing to let their developers move on. we got Ghost of Tsushima, we got the new Spider-Man games (not a new IP but a new take on an established character by a new developer), we got Horizon Zero Dawn, we got Uncharted (back when Naughty dog moved on from Jak and Daxter), we got God of War 2018 (which again is not a new IP but so different from its previous iterations that it might as well be.) The point was that these companies try new things. While that includes new IP it also includes new takes on old IP. 

Not every game needs to be a microtransaction-riddled live service or another shooter that you can't tell from its predecessor or a racing game that, to the onlooker is just a prettier version of last year's model. 

Of the three major companies (Sony, Nintendo, Microsoft), only two of them can be claiming to create new and unique gaming experiences with any semblance of frequency. Sometimes that means making new IP, sometimes it means mixing things up. 

Microsoft needs more identity. and if they're gonna nail down the FPS market then I think they should. Because they're not being creative right now, they're just buying up the competition. There's a reason I'm so critical of them overall. They aren't actually bringing anything to the table, they're just grabbing platters and saying 'mine', and getting to chose when others get to have a bite of their meat. I hate metaphor but that's what it feels like. Sony and Nintendo are bringing delicious desserts and delectable dishes, each one made with love and care, while Microsoft brings a well-cooked but kinda bland roast, then offering to buy up a bunch of the dishes brought by the third parties and taking credit to mask the fact that they aren't actually all that good at cooking. They try, and they have the best equipment and the most money and genuinely seem to want to make the customers happy, but they're actually not that good at it so they just buy up IP from other people. 

IT's an apt metaphor, even if I hate metaphors. 

"Of the three major companies (Sony, Nintendo, Microsoft), only two of them can be claiming to create new and unique gaming experiences with any semblance of frequency."

Yeah... I can totally see how GoW, HFW, GoT, R&C, Spiderman and TloU can be considered more.. "unique" than Pentiment, As Dusk Falls, Gears Tactics, Halo Wars, Sea of Thieves, Grounded, or Flight Simulator. I mean, just look at the plethora of games similar to Sea of Thieves that we have on the market.

"Not every game needs to be a microtransaction-riddled live service or another shooter that you can't tell from its predecessor or a racing game that, to the onlooker is just a prettier version of last year's model." 

Huh...