Fate of Ecash if RSA is cracked?

[ichudov@algebra.com (Igor Chudov @ home)]

Hello,

After reading Comm. of ACM and Schneier's book about ecash,
a question arose: what if the underlying public key cryptographic
scheme gets broken somehow? Suppose, for example, that someone
discovers an ultra-fast factoring algorithm or something like that.

What would happen with all ecash that's been issued? Of course
criminals would be able to forge large amounts of authentic-looking
ecash, so banks should not be honoring requests to convert e-cash into
real cash.

I apologize in advance is this question is silly, and will appreciate your
corrections.

	- Igor.