The existing Prime & Megs don't really fit in with the other MPs. I wouldn't be surprised if TT feels that there is a lot of future in the MP line, and thus needs to correct the first two molds to be proper frontmen for the line.

I still can't fathom what alt mode they'd give a Masterpiece Galvatron or Soundwave. It's not that I wouldn't want one; I just understand the challenge.