You do not drop him or refuse to pay him and gamble on nothing. You start drafting QBs, making reasonable deals like Lance, and you try to develop them. But SB or not, you don’t let a successful starting QB go until you have his successor ready. There are no guarantees, but if you see a young QB in practice that you think has what it takes, then it’s okay to make a move. That’s why you should be taking a mid to late round flier every 2 years on QBs. If you don’t think Dak is good enough to take you to the promised land, then it’s really stupid to have guys like Cooper Rush (lack of talent) and Grier (age) as backup QBs. You need to be developing guys whether they replace your starter or not.