If we ignore the deleted scene from the SE, Jabba is repeatedly only mentioned by name in the OT, only to be revealed in ROTJ. That clearly worked, and worked well. So the same logic could be applied to Yoda.

If we think about what Yoda's character represents aswell in ESB, his presence doesn't make any sense in the PT as he is.

I wonder how much could be added to the PT through additional characters, subplots and dubbing? Introducing a few tricks like Dooku wearing a mask until a big reveal in AOTC could allow more shots of him to be added. Also if we consider ROTJ to need some additional treatment, then maybe some added PT subplots could manifest in ROTJ 30 years later (with reoccurring sub-characters, locations etc)