I'd certainly like to see some of the Pretenders characters get 3rd party, or Hasbro updates. I'm not too beholden to the original gimmick though, and liked what was done with Bludgeon and Skullgrin. A Stormbringer or TFPrime videogame version of Thunderwing would be cool. The bigger, later Pretenders were less organic than the earlier ones any way, and the Decepticon Pretenders in general could probably work fine without their shells being given the full treatment. That said, any Stranglehold update would have to keep his moustache or I'd be the sad bunny.
As to a proper update of the outer-shell+inner robot concept, I'm sure it could be done, but can't think of a good way that wouldn't result in either a huge, unwieldy and expensive shell or tiny and unsatisfying inner bot. There was a customiser on the forums making Pretenders out of Scout class bots and I think mostly superhero figures, and it worked okay for a custom project but would likely be quite pricey as a 3rd party venture, and I'm not sure there's enough interest in the characters to warrant it.
assembling a Neo-G1/TF:TM cast. Please PM if you have (or know of) the following at a reasonable price: Classics or Henkei Astrotrain, Sunstreaker, Sideswipe, Blurr, or 3rd Party iGear Ratchet and Ironhide.
Also looking for Universe Repugnus and Overbite, Frostbite and Longhorn and any Webdiver toys.