I read somewhere that Welker's auditioning for the movie, and that the jury's still out. But given his history with the franchise, his status as the go-to voice guy in Hollywood, willingness to do stuff far beneath that status, and the fact that pure nostalgia is driving this film, I'd say it's his if he wants it.
This movie MUST go for the thirty- and twentysomething guy who grew up watching weekday afternoon cartoons, and the vast majority of these guys aren't the Transnerds we hate from the online domain. The designs have to be contemporary but easily recognizeable, and the voices need to echo the old series. From what I've seen and heard, that's the aim.
And fuck a Kaye and Chalk. Call 'em when they decide to do a Beast Wars movie.