Needs to demonstrate he can stay healthy first off. Rams are not patient when it comes to production, especially with guys who are paid. Last season wasn't fully his fault, I don't think he played particularly well for most of the time he was healthy but protections were terrible even before the injuries began up front.
So he just needs to put up a nice reminder year where the Rams see the guy they got in that playoff stretch. And hopefully they are serious about the run game, which would help to keep him healthy. Some of that is going to be on the team for sure to provide good OL play and keep defenses guessing with that ground attack so if that happens yeah I could see him finishing out his time with us.
If he misses significant time I think the Rams package picks including that first rounder to move as high as possible and take a QB. Still might do that even if Stafford plays well but I expect how well he plays and whether he can keep his health going will factor in to those plans.
I expect he's going to put up a really fine season either way. Only concern I have with him is health.