I think they'd have enough characters. Especially if they do "future" marty, 50's marty, etc. Also, there is doc, his mom, dad, brothers, sisters, kids, biff and gang and that teacher who is bald (what was his name?). I think they could make enough. Alot of the other games just use the same character in duplication.
I actually wrote lego and tts and asked them to make a lego back to the future..and a lego buffy the vampire slayer, but that's a different story :)
LEGO has a license for all of the current games as actual toys. Star Wars, Indiana Jones, Batman, Harry Potter, and Pirates of the Caribbean are all current or past series. There is no compelling reason to make Back To The Future or Buffy LEGOs, so they certainly won't make a game.
How about a Lego "James Bond" game? They could have Lego versions of Connery, Moore, Brosnan, Dalton, et al., not to mention all the villains that could be unlocked. There's probably a whole bunch of licensing reasons why this game wouldn't happen, but I think it'd be a lot of fun!
ya i agree, 007 would be the best LEGO franchise move ever....they'd release them in 3's so we'd get to play through all the movies over the course of a few game releases, but ensuring that we get long games, not the short levels that Batman and Indy had