It's fixable with a license change, but in practice that's impossible for large projects. Without a CLA, every individual who's contributed is a copyright owner. If you can't get every single one of them to agree to change it, then the license is stuck. And it doesn't matter if the reason you can't get them to agree is because they've become uncontactable or died.
I think copyright is inherited by the heirs (in most cases relatives of the deceased) and carries on quite a long time after death. So the relatives may actually sue you, and any discussion WRT relicensing would have to be addressed to them.
I actually consider putting something into my will that states that all my open-source contributions are relicensed to "public domain" (CC0 [1]) once I die.
Its also possible to transfer your copyrights before your death. For example to the FSF or to Software Freedom Conservancy. I hear there are tax implications for copyright bequeathment, which is why transferring copyrights is preferred.
