If Picard & Crusher retire, that only leaves Worf and Geordi from the original TNG cast. (And sure, Data could return to the Enterprise
, but his character arc seems to be moving away from that right now.) I'm not opposed to characters who originated in the novels like T'Ryssa or characters who had small parts in the TV series being expanded upon like Taurik, but when you reach the point where those type of characters have replaced nearly the entire crew then it really isn't TNG anymore, it's become the equivalent of New Frontier or SCE, so it should be rebranded. Kind of like Jefferson Airplane becoming Jefferson Starship.
Not that I expect the TNG line to actually be renamed (Star Trek: Jefferson Starship Enterprise!); more likely new stories of Captain Worf on the E-E could still be included in events like The Fall, but any books under the TNG banner could then take place at any previous point when Picard was still in command.