My biggest issue with Lance is that they'd have to make the 5th year option decision after this year, which would be complicated even more if he were to sit behind Cousins for a year.
I used to think that Shanahan was a guy to listen to when he has a thought about a QB, but I'm backing away from that thought a bit. Not because he hasn't had capable QBs, but he seems to go out of his way to get not terribly mobile pocket passers. Kaepernick is out as soon as he arrives, then he wanted Cousins, goes with Garoppalo, Brian Hoyer, CJ Beathard, Nick Mullens, Brock Purdy and now, his most mobile QB, Sam Darnold. Lance sticks out like a sore thumb, why did they trade up for him when he's clearly not what they were going for?