I think Byrne is in a position financially to do what he wants when he wants to. This, plus I also think he is the type of person to puff his chest and scoff at the big 2 until the "right people" are in charge b/c he doesn't need them to pay his bills.
If he were to go back on FF I'd be hesitant to buy it. The way he draws the Thing these days isn't really grabbing me. He had him perfect on his run. Now he's got the detached eyebrow which I don't like. I liked his domed head version the best. He draws Reed too cartoony too.
The best way for him to really make a come back would be to do something that's never been done but a fanboy's dream like team up with Neal Adams for a 12 issue Batman limited series. One of them pencils and the other inks the first 6 then they switch for the other 6.
Byrne also writes it.
I'd also like to see JB do something different at the Big 2.
At Marvel I'd like to see him handle Dr. Strange, Thor, Silver Surfer (on an ongoing basis), & Invaders.
At DC I'd like to see JB work on Batman, Flash, Green Lantern, & Captain Marvel.