It's all relative. The Phillies carried weak, if usually defensively stronger, 3B for a long time. But they had such big bats in the rest of the IF during those periods. Franco is supposed to be one of the 2-4 guys they can count on while others develop and prove themselves. If he's not, that doesn't necessarily mean giving up on him, but it means they'll need more, and more quickly, from a spot like 1B or LF.
Kendrick can play third, if it's just about giving Franco a break. If Crawford was ready you could move Galvis there, at the moment he'd be an upgrade. But nobody needs to go, expectations for this team ranged from 62 to 81 wins, trending towards the latter isn't going to cost anyone their job in the short-term.