It doesn't crush his value. Hurts a bit, but more for the loss of flexibility, not because 3B is that much deeper than 2B or anything.
2014 trueAV MLB wide was .261 for 3B, .259 for 2B. Basically the same. The gap was a bit larger the two yeas prior, but in 2011 2Bs actually outhit 3Bs. It's not what it used to be back in the golden days when 3B's were just 1B's with arms, and 2B's were just shortstops with noodles.
He was also pretty adequate at 2B so there's a decent chance that he'll get enough games in there at some point, if Wong gets hurt or sucks or whatever.