Right, but if they're going to cut him anyway, then they'd presumably be willing to do a trade for virtually nothing. So if there's more than one team interested in him, then one of those teams can simply offer SF some very low draft pick to take him off their hands, and scoop him up before he hits the open market. OTOH, if only one team wants him, then that doesn't work. They're better off waiting SF out.
Well, that's the other reason that no one's trading for Smith -- no one wants to give up even low-end assets to take on that contract, which is pretty heavily backloaded. It just isn't going to happen. The quarterback market may be thin this offseason, but I don't think teams are going to get moronic for Alex Smith.