Our favourite Nostradamus returns for a feast.

This is what he had to say about the Microsoft-Activision deal:

Microsoft had a vision years ago that I thought was stupid, that they were going to come up with a subscription service, and everybody would pay them for the right to play games. And they just didn't have very many games.

Then they went on a buying spree, and they bought six independent studios, the biggest of which is Obsidian. They're very, very good. But then they bought Bethesda, which is a giant studio, and now they're buying Activision. When they're done, they are the fourth major game publisher in the US. So they're going to be giant, and they're going to be in a position to actually support their Game Pass subscription.

Their future vision is, let's eliminate the console. Let's use the cloud, and let's deliver games to any screen that you have. And that potential market is 3 and 1/2 billion people. So I don't think they'll get that many Game Pass subscribers, but will they go from 25 million to 100 million? Yes.

https://wccftech.com/game-pass-to-reach-100-million-when-activision-games-are-added-says-pachter/

And this is what our favourite Jez has to say about it:

Michael Pachter is right

Pachter's analysis focused on Activision-Blizzard's potential for Xbox Game Pass, but there are various other avenues to growth that could take the userbase even further beyond 100 million. 

There are 3 billion gamers in the world right now, and while global infrastructure isn't quite good enough to reliably stream Halo Infinite multiplayer from the cloud for everyone, there are hundreds of games that play extremely well even on modest connections right now. Global internet speeds are constantly creeping up, with Microsoft and its massive Azure cloud well positioned to be at the fore of this brave new gaming world. 

Pachter is 100% right about Xbox Game Pass hitting 100 million users in the future, though, considering it's already at around 25-30 million without some of the major pieces in play. 

https://www.windowscentral.com/gaming/xbox/could-xbox-game-pass-really-hit-100-million-subscribers

I mean, it's not unrealistic. Game Pass subscriptions are clearly only going up and that's without really any major hitters dropping yet. Doesn't take a rocket scientist to figure that out.

But to go straight from 25 million to 100 million just because of ActiBlizz deal? No that's going to take at least several more years to reach those kinds of numbers. Not to mention stupidly consistent releases, which remains to be seen.

So... Game Pass is doomed?

But to be real a minute it doesn't seem from that quote like he's actually saying the service would reach 100 mil as a direct or immediate result of ActiBliz games as the title of both this thread and the article imply and which is of course ludicrous. The final part where he mentions 100 mil seems to be more about their potential far down the line.
But even giving him the benefit of the doubt on that one, 100 mil is still a very large number to throw around at this point. I can't see that happening unless the gaming subscription market as a whole completely explodes.

50-60 million gamepass subscriptions by the end of the Xbox Series lifecycle...sure maybe. 100 million soon after closing on Activision, not a chance.

I still don't think it's consoles / PCs holding back the masses from jumping into 'bigger' games. Streaming isn't going to turn the mobile gamer into a consumer of longer more complex games you have to subscribe for. It's more for the existing console / PC gamer that they can now also enjoy their games on a mobile platform, albeit with some hurdles.

The deal isn't going to turn the entire existing gamer base into game pass subscribers, and I highly doubt gamepass is making big inroads in the blue ocean. It will grow sure, might shrink again, grow again, become cyclical with big releases.

Sure, eventually. In maybe 10 years or so I think.

Since he doesn't specify a time frame he's technically not wrong.

I don't see 100 million subscribers as a stretch in the long term. I think I'd put the over under on when we get there at something like 8 years from now.

If they do really well, and global internet speeds and the number of people with reliable internet access continues to increase, I'd say 6 years is something like a best case scenario. However, it appears that there's going to be a substantial slowdown in the global economy in the immediate future, and that will likely slow down growth of a luxury subscription service, and slow down the rollout of better internet infrastructure.