I think in my most ideally imagined edit, Yoda would be replaced by Dooku as a jedi in TPM, and then Yoda would just be cut from AotC and RotS, with most of his role being filled by Mace and possibly another jedi. As for having Yoda be built up until ESB without shedding any light on it, I would rather he only be referred to twice at most, a passing comment from Obi Wan that Yoda trained him, then maybe another comment by someone suggesting Yoda was the greatest Jedi but is no longer with them. This could even be interpretted as Yoda being dead, so the audience wouldn't be waiting for him to pop up, and would add to the excitement to see him in ESB.