Re: IF Wolverine 3 happens,what should be the story of that movie?
Old Man Logan would definitely work, but not yet. Save that for when Jackman finally gives it up.
For now, I really want them to touch upon Daken. It's too big a story not to tackle at least once, particularly if they play Daken to be as unlikable as he is in the comics. Seeing Wolverine take him out would be a crowd-pleaser, as well as an interesting development for Logan, him taking out his own son.
I also think we need to get Sabretooth in the mix. X1 Sabretooth had the right look, but barely any dynamic with Logan. XMOW Sabretooth had good dynamic, but that movie is the bane of my existence. I've yet to see their "relationship" get tackled in a satisfying way yet. They can bring back Liev Schrieber for continuity's sake, but as long as they buff him up.
Omega Red would also be a possibility, but I'm not a big enough fan of his character to know how they'd tackle it correctly.
As long as he either gets paired up with Yukio, Rogue, Kitty, or even Jubilee, along with anything I just mentioned, I'd be good.
If any character has ever earned the right to enjoy a happy retirement, it is Bruce Wayne. Nolan ought to be commended for caring enough about the character and believing enough in his own vision to provide a definitive, satisfying ending to the story of an ordinary man who turned tragedy into the motivation to accomplish something extraordinary.