JFI, unless Stafford retires I don't expect Jimmy Garoppolo coming back to the Rams. The Vikings will come hard after him to replace McCarthy in Minnesota. Already knows the offense and is a huge upgrade over McCarthy. In fact, I would not be shocked if McCarthy is traded.
Also FWIW, I was wrong on McCarthy, really thought he would be a good NFL QB, obviously that is not the case. I don't see the Vikings making a move on any other QB that is available, so Garoppolo makes perfect sense in Minnesota next year.