Eh, I'm more optimistic. I think they will fix things as much as possible. Forza is an important part of the Xbox brand, and if they really want to continue this marketing merger of Xbox and Windows then they need to build confidence. A poor performing Forza game on PC doesn't do that.
Part of my optimism is watching what they've done with BC on Xbone. Games went from being noticeably worse than running on 360 to being better than on 360. It took a few months to get there, but they did.
Also... I know this is playing with fire to say... but I've been running FH3 completely maxed out ultra everything 2560x1080 on my i6700k/n1080 PC. No problems or frame drops. But of course, that's because I set it for 30fps. Yeah, I know 60fps is ideal, but this game isn't bad at 30, although don't get me wrong, I would prefer to lock it to 60 but I hate frame drops and stutters.