B&N should set up a bidding war between Amazon and the Big Five publishers. It's in the Big Five's best interest to keep B&N alive, but to keep it out of Amazon's hands. And yes, there are anti-trust issues all over this scenario.
Both of those ideas have been floated, but not necessarily by either Amazon or the Big Five.
Not so much for books but for some of its either merchandise, Amazon could really use show rooms, and B & N still has leases on lots of well-placed storefronts. (Think Amazon fashion lines, for example. Some people do actually like to try on clothes before they buy.)
The Big Five, on the other hand, could make good use of B & N's online presence. Sure, it doesn't have much market share right now, but what would happen if the Big Five started playing the exclusivity game? Stephen King's latest bestseller--ebook now available exclusively at Barnes and Noble! If the Big Five did that with enough of its catalog--even the whole thing if they were being gutsy--how fast would Amazon lose market share? To avoid being too exclusive, the Big Five could offer it everywhere except Amazon. Unfortunately, that might work so well that it wouldn't be to our advantage. Amazon facing competition--good. Amazon collapsing--bad.