Apple has over $25 billion in cash on hand; Amazon has over $8 billion. $50 million is chump change to those guys.
While I do agree that competition is good, and hope that Kobo does well, the chances of them lapping B&N is not that high -- especially since their biggest US source, Borders, is gasping its last breath. Even if B&N bombs out somehow, it's entirely plausible that Amazon or Apple will reap the lion's share of the Nook'ers. (Or should that be "Nookies?"
It'll be a remarkable story.... if and when they turn a profit, let alone achieve a sustainable position in the market place.