I'm betting they'll split the movie onto two DVDs. They split the ultimate cuts of the LotR movies and Watchmen, with the extended footage and TotBF, will be approaching three and a half hours in length. So:
Disc 1: First half of the movie
Disc 2: Second half of the movie
Disc 3: Special features
Disc 4: Brand new special features?
Disc 5: Motion comic
Someone else mentioned them splitting the movie into two parts for this release, but I don't see why that would be necessary. Gone With The Wind is almost 4 hours long and has been released on a 1-Disc DVD This movie could also be released on a 1-Disc DVD, no problem at all.
In addition, the Complete Motion Comic does
have to be split onto two DVDs (see the standalone release for evidence of that).
My guess is that it would look more like this...
Disc 1: Watchmen: The Ultimate Cut (Includes Tales of the Black Freighter spliced into the Director's Cut of the movie, along with the Two Bernie Cutscenes)
Disc 2: Tales Of The Black Freighter/Under The Hood + Special Features carried over from the previous release
Disc 3: Either Theatrical Cut or Director's Cut + Special Features carried over from the previous release OR No Previous Cut of the Film, but an entire disc of new special features
Disc 4: The Complete Motion Comic Chapters I-VI
Disc 5: The Complete Motion Comic Chapters VII-XII
it doesn't turn out like that. I don't mind having the previous releases included, but I would prefer more new material for this release that hasn't previously been available.