I know when we get a company-wide overstock of a discontinued or clearance product, often times we get special vendor support, either in an overall reduction of cost, or back-end reimbursement for moving old product below cost. Obviously we don't know for sure what broke Vanns, or why Newegg is able to sell Polk Monitor speakers so cheaply, but perhaps something like this is/was at play here.
I will agree, though, that CE retail is a changing landscape...it just seems that there is more certainty for extinction rather than the possibility for adapting.
People want nice showrooms, display models to interact with, large selection, knowledgable salespeople and customer support, but don't want to pay extra for it. Which is why B&M retailers tend to pay their employees so little, and it goes around and around in circles.