Suddenly scrapping everything to do with the franchise based on one break-even movie would be a wild overreaction. I think this is actually a pretty good place, in a way, for TF to be faltering at the box office. If Bay really is stepping away, and Bee Movie does well, then Paramount sees there's still a market for TF without going purse in hand to Bay's house for the next main sequel.
If Bee Movie is a flop too, then I can easily see us getting a few years off, and probably a reboot, a result to which my personal response largely depends on the TF designs. I'd like to say I have faith that they'd never try to trot out big cartoon Dery designs on a movie screen, but reboot desperation does a lot of things.
Speaking of reboots: Transformers made all its money as an action-movie franchise. That's what they'd be rebooting it as. I think there's this weird idea among certain segments of the fandom that a reboot would suddenly get us a movie that's all about robots having conversations, and there's no way - the robots cost way too much for that right off the bat, even if you ignore that that's not what audiences go see. (Those of you who are about to insist that's not true are welcome to list the top-grossing non-Disney movies without a principally human cast.)