Sunset sales have not been crash hot. I do not see it cracking over 1 million units sold worldwide in its lifetime so it would not surprise me if they ported it over to PC. Let us not forget that Sunset had big push from Microsoft via prominent adverts on popular gaming websites(IGN etc), Youtube and the exclusive white X1 bundle(which could not be purchased without the game itself). Given all these factors I see Sunset sales are disappointing which is a shame because the gameplay looks inventive and very fun. Not a game I would purchase a console for but if it were available for the console I own(PS4) I would have bought it day zero.

MS still thinks Dead Rising 3 and Ryse are only on Xbox One http://www.xbox.com/en-US/xbox-one/games/dead-rising-3 http://www.xbox.com/en-US/xbox-one/games/ryse

No they wouldn't get money from every copy sold.
Unlike Consoles, there is no single "owner" of the platform in order to extract money from every singular piece of software that is sold on the platform, this is why PC games are cheaper than Console, there is no Microsoft/Sony/Nintendo Tax on games.

However, the way Microsoft makes Windows games financially feasible is one of customer retention, if they can maintain their OS monopoly on the PC for gamers, then gamers will continue to buy Windows, which means money in Microsoft's pocket indirectly and less users for MacOS/Linux and it's derivatives.
Converesly, if you own Windows, you might be enticed to get an Xbox, Windows Phone etc' as they lure you into their locked-down ecosystem.

The only time Microsoft actually makes money from a PC game sale is when they are the publisher/owner/developer of the game or if it's via the Windows 8.0/8.1/10 App stores.

In Sunset Overdrive's case they might actually benefit from the extra attention that a PC release might bring which might entice more users to buy into the Xbox.

Lastly, the PC is a larger market than the Xbox One, Playstation 4 and WiiU currently, there are more gamers, there is more money floating around, so if a game was expensive to make, you would be silly to exclude the largest and "fattest" platform, these are business's not charities afterall.

Just wait, probably same month next year to be sure

I know that there are tons more people who have PCs, but the sales for console style games seems much lower than even on Xbox One doesn't it?

So they would make money on Forza Horizon 2 then. 

I don't think so. These are system selling games.

Indeed, but they wouldn't make a cent from say... Half Life 2.

That's because PC gamers generally like PC games, not console games.

Think about it, Call of Battlefield: Generic Warfare sells like hotcakes on consoles, but only relatively modest on PC.
Yet if you glance at something like... League of Legends or Dawn of the Ancients 2, their fanbases are monolothic and fanatical.

That's not to say console games don't have a place on PC, games like Skyrim and Oblivion (Origionally Elder Scrolls was a PC exclusive franchise.) sold incredibly well.
Then you have games like Diablo 3, which sold better on PC than all console paltforms combined.

 Lastly, PC game sales tends not to get tracked by the likes of VGChartz, how could it when the majority is sold digitally and never disclosed? Not to mention, PC games have longer legs.
For example... Lets take the origional Fable, it was released on PC over a decade ago, sold fairly well, then it was brought to Steam, sold some more copies for little effort, then every time it's on sale, the sales rate picks up dramatically hitting the top of the sales charts, over the years, I wouldn't be surprised if the origional Fable sold better on PC than on Xbox. - That's in stark contrast of a console game, where... After release it pretty much falls into obscurity never to be heard from again.

Besides, most of these "games" already have most of their costs sunk into the initial development for the consoles, porting to the PC is generally not a hard or dubious task, so the sales on PC are generally mostly profit, not to mention a developer receives more profit for a game sold on PC than console anyhow. (I.E. No Nintendo/Sony/Microsoft tax.)

Sunset Overdrive yes

Forza Horizon 2 no

I've argued a lot on this forum about Insomniac's desire for independence and how they want their own IP. They wouldn't do this deal unless they did

They are publishing it on XOne only. Nothing is stopping Insomniac to take the game directly to Steam or Origin (or even PS4) without Microsoft's interference.

Not saying that they will. Honestly, I believe Insomniac would profit the most by porting it to WiiU.