So....it's not as if you have no idea what time your return window will be. It's right there, up above you, over the FP machines. So...if you don't think you can return within that particular window time, then don't take a FP..just ride now and take your chances later.
Here's the thing...yes, we were always able to use the FP later, after the window had come and gone. BUT....the back of that FP did ask that you return within the time stated, and the front said no early returns. Yes, the CMs were instructed to let us use them late. BUT...on the other hand, if there had been any kind of issue with an attraction, the CM would be perfectly within their right, and Disney policy, to not allow someone to return hours after their FP window had come and gone. No, the guest wouldn't be happy, but it would still be enforceable. Only at Soarin' did I see that happen with any regularity.
So, now we can't use them late. That's really not a huge issue. If you're eating at a particular time, and will be cutting it too close, then maybe you shouldn't take a FP. If an attraction breaks down, and you get stuck and then miss your return window, they will usually accommodate (or accomodate

) you with a use anywhere FP. At least that's been my experience.
It will be interesting to see what happens today and over the next few days. But in all reality??? You have to realize that the vast majority of park guests had no idea you could use the FP after the window closed. I can't tell you how many times I tried to give away FPs as I left the park...I was turned down about 60% of the time. The reason??? Oh, those are no good anymore. The return time was hours ago.