You have to think that Andrew Berry is going to want to set the market for the 2018 QB class, and not let it be set for him.
At least match Stefanski's contract length. Make the marriage official. It's got to get done to send a message and secure the future success of the team. They could potentially keep his cap number the same this year, and figure it out from there.
I think the future money can be kept in the 20s for annual value, possibly around 24-26 right now. But if we wait and he goes on to win 1 or 2 or 4 playoff games and wins NFL and SB MVP, it's up to 40. Sliding scale