It's starting to lean more towards being something like TF2 Devastator or Metroplex - big but very simple.... and a general release, if a store wants to risk such an expensive item.

It's certainly interesting re-watching that Hasbro video in Paulbot's post, and wondering if the Gen1 Devastator and Defensor were there intentionally, as a hint of other new Combiners, or advance warning of reissues.
Because all the other toys behind them (which is an intentional display, not someone's random cubical shelving), are mid 2014 to early 2015 toys... making it an obvious question - why are those two Gen1 combiners intentionally placed there.