They've said that it'll be entirely based on the existing 3rd ed system. Hopefully they'll tidy up some sore points, like the overpricedness of Shrinking, the messiness of Affliction, and the lack of anything resembling 2e's Independent modifier, which sorely limits the flexibility of the point-buy power building system. But i wouldn't bet on it. It sounded like they were just going to do a straight system lift and drop.
I wonder if GR made any sort of attempt to get the Marvel licence at all? It would seem to make sense, given their experience with licenced properties and M&Ms status as one of the big superhero games, but Marvel went with something completely brand new from Matt Forbeck instead (maybe they wanted to do it all in-house rather than licence out?) Or maybe GRs history with making a DC game counted against them there?