First, B&N isn't in any peril of "going belly up" in the near future. Financially, they're very strong with a fairly low debt load (unlike Borders, which is running almost entirely on borrowed money). They're also making the hard choices and preparing for the future where store sales of printed books aren't going to be the big money-maker.
DRM-wise, B&N has opened their DRM via Adobe. Anyone who makes an e-book reader can make it B&N-compatible by using the current version of Adobe Reader Mobile. A number of readers have been announced that are B&N-compatible, but the recent round of price-cutting has seen most of those new products slip out of sight. The Pandigital Novel is available at Kohl's, but initial reports are that it's nearly unusable.
You mentioned iRex, and the iRex DR800S/SG is another reader that is B&N-compatible, but iRex is struggling financially. Besides, unless you want the big screen, it'd probably be cheaper to repurchase your library of e-books.
Adobe has said that they will update Adobe Digital Editions this year to support B&N's DRM.
That said, right now there aren't a lot of alternatives for reading B&N DRM-ed e-books. There's the B&N reader software. On the other hand, the NOOK can read Adobe EPUB format.
Added: Whitecat500, check for a private message.