This.  When (or more likely) if ECC is compromised the most likely scenario (based on prior crypto attacks) it likely will be a partial compromise.  That is private keys must be brute forced but can be done so millions or maybe even billions of times faster.  That means that the day 0 threat to Bitcoin will be minimal.  The network will operate for a while with "legacy" addresses and new "strong" addresses.

In time though those legacy addresses will represent a risk.  A method to sunset that risk may need to be devised.  Even then it will be controversial and require some thought.  To change the protocol today in such a fundamental manner is just asinine.