[jabbany]

No idea, but I could imagine something where you have a period of time on the chain where both signature types are allowed, and people can just migrate their coins by transferring from the old wallet to one based on the new signature system. Then after a certain cutoff, the chain can phase out the old signature system entirely.

Of course this only works if the old system is just "weak" rather than "broken". There is no way to recover if the signature system is completely broken, but if ECDSA is broken then we have more to worry about than just Bitcoins.