Cano at least can still hold down a valuable defensive position. He's never beent a great glove but he can pass. Replacement level offense for a 2B is a pretty low bar. The real problem comes in a couple of years when he's no longer able to field his position. Where can you move him then and can he hit enough to justify the roster slot. It's kind of like the case of Brandon Phillips except with a longer tail.
His UZR for his career is pretty firmly negative. Glove-first middle infielders are not tough to find if you're not expecting much offensively, but those are guys you can get cheap or via your farm system.
There are, I'm sure, some things they can do with him to forestall the inevitable, but ultimately it looks like a losing battle.