...I do hope they get Shatner for the 50th. It would be fun, and the man is a blast to watch.
I'd like to see Captain Kirk again. Kirk; not Shatner. If Shatner showed the commitment to lose the weight, performed the part instead of gracing an audience, and kept the hair in check, then right-on. But the last thing I want is to be taken out of the story, please.
Kirk has given plenty to Shatner; nothing is owed at this point. If fans just want to see a favored actor, Trek can do a side-project like Who did with The Five-ish Doctors. It was touching, smart, and fun.