I think this has already happened to at least one whale.  The guy who was putting up 100k XMR sell walls back down below 200k. 

Big walls ended up getting eaten, and then we rocketed higher.  I havent seen any walls nearly that large since, so I am guessing this guy got left behind, and now has either no xmr or a significantly reduced amount that he is no longer willing to part with.

Again, the recent price decline didnt seem like one whale dumping, but rather 100 traders all dumping on the same day as they got spooked by a bitcoin rise, and then some of them dumping put the other's margin positions in peril, which resulted in a chain of dumps to eliminate margin.