> It's not asking for trouble to avoid relicensing until you can see the new license.
Legally speaking, you're right.
Practically speaking, if you're running a project with a lot of contributors, hunting them/their heirs down and getting buy-in for a license change could be a huge project in and of itself.
In late 2012, the OpenStreetMap project changed it licence from CC to the current ODbL. Every user who had contributed to OSM had to be contacted and asked if they accepted the new one, and if not, their contributions had to be deleted and retracted. It was very annoying.
Legally speaking, you're right.
Practically speaking, if you're running a project with a lot of contributors, hunting them/their heirs down and getting buy-in for a license change could be a huge project in and of itself.