Even if Calvin Johnson doesn’t want to play this season, it would still be in his best interest to be cut by the Lions. Mike Florio explains via ProFootballTalk:
“The thinking is that Johnson didn’t calculate the move, and that at this point he genuinely does not want to play. But, as the theory goes, Johnson has realized while taking time to mull things over that, if he’s going to retire, it’s better to retire not as a Lion but as a free agent. If he retires as a Lions and later unretires, the Lions will control his rights. If he retires as a free agent and later unretires, he can sign with any team he wants, unimpeded by the Lions.”
The Lions don’t really have a choice because of the high salary Johnson carries into the 2016 season. Detroit also wouldn’t be able to ask for his signing bonus back if he is released. So Detroit really needs Calvin to retire and Calvin really could benefit from being cut.
The most likely scenario seems to be Johnson being cut in March and still retiring, but never underestimate that midseason call from Bill Belichick.