This is Purdy's 3rd year, so why do they need to sign him to a major contract next year? He could easily playout his contract and then either resign with them or play on the franchise tag, as I don't see him going anywhere unless he completely falls apart.
From what i am hearing McCaffrey is being shut down for the preseason because of a nagging calf strain, the same calf strain that slowed him in the playoffs and super bowl last year. Those things can linger all season, not expecting much from him this year.
I don't necessarily feel like Purdy's contract is what will derail them. It is all the other's that need to be resigned. Like their starting CBs, Hufanga, Greenlaw, Deebo is coming up again, along with Kittle...I just looked it up and they will finally need to start making financial decisions on who stays and who goes.