oh fun, every detail requires a theory adjustment. my thoughts on the game containing 4 Belmonts battling Dracula each 100 years apart just went out the window with the revelation that Simon is Trevor's son. i was imagining two other time periods with equal weight to them as Trevor and Simon's for the other two characters, but now not so much. perhaps the other two characters are just an extra "mode" of play like Julius mode that you can play with once you beat the game, maybe without much of a story. or worse, they could be playable in the main quest, but only in a single tiny area like Laura. but regardless, i'm glad they are putting 4 characters in the game.
EDIT: Nevermind, reread more of the Nintendo Power article and it still seems like all characters will have their own time periods within the game.