why exchange for dollars at all? afterall, a value of 10K would presumably entail a great deal more of merchant acceptance, etc... than we currently have - you could just buy with bitcoins whatever it was you were planning to spend the dollars on.
and if you did decide to cash out, why on earth would you want to do it all at once like that?! i'd take my time about it, and also hold onto some of them, the price could go up further if it had got that far!
It seems like some people have a bit of an obsession with cashing out at certain price points, overlooking the fact that for it to get to those price points, there must still be good reasons to keep your money IN bitcoin...i.e inflating fiat currencies, it's increased confidence and acceptance as a transferable, secure store of wealth a bit like gold etc...