They are funding the game, so they will see some revenue back on any of the versions of the game most likely (SFV).
Just because they may not be doing the PC port for SFV doesn't mean that this Kickstarter for Shenmue are the funds for a PC port.
I would imagine that Sony's revenue stream for both games would be entirely restricted to the PS4 side of the equation. Will they likely see a far larger share per copy sold on PS4 than other 3rd party titles or independent software published by Sony on PSN? Most likely, but I think it would be inaccurate to assume Sony is a financial stakeholder across the board.
The best way to view Sony's role in Shenmue, from how I see it at least, is that they are:
1. giving Yu Suzuki the same resources they would provide to a pub fund/indie studio group announcing a PS4/PC exclusive title. This likely includes a suite of development kits, already established software libraries, and regular technical support.
2. the biggest behind the scenes Kickstarter backer of all time. Sony wants Shenmue 3 to happen. They don't own the rights to make it, Suzuki isn't on their payroll, and they likely don't see much real chance or value in trying to make either of those happen. Much like all of us they're putting a nice chunk of change behind the promise of Suzuki making Shenmue 3. If Suzuki inexplicably calls it quits a year or two from now they'll be out their investment just like the rest of us. The only difference is that theirs will be a seven to eight figure number while even the most generous of us will maybe make it into the very first stages of five figures.
The suggestion that this is Sony using Kickstarter to effectively collect money from consumers preemptively assumes that Sony has complete control over the Shenmue IP. They do not. They don't even have the rights to use Shenmue in any real form. SEGA owns the IP, they've given Suzuki quite a bit of latitude to play with in his pursuit of a final chapter, but ultimately they control the franchise's fate into perpetuity. If Suzuki walks away Sony can't finish the game. If Suzuki dies Sony can't finish the game. If the game is a real stinker but Suzuki is done and wants to push it out the door Sony can't polish up the game. Sony's role is less powerless than the average KS backer because they're a platform holder and have a working relationship with Suzuki, but their fiscal involvement isn't buying them much else here.
Also, I'd much rather see the Shenmue 3 that collects $5M to $10M on KS and has a comparable amount of cash slipped in the back door by Sony (along with a bunch of free development resources) than the Shenmue 3 Suzuki could make with just what he gets from Kickstarter alone. It will likely result in a significant upgrade to the quality of the title, which is ultimately what really matters.