In reply to John Teague.

I envision a future where WordPress will automatically perform checks for compatibility issues when an update like this occurs, and when it finds one, will automatically notify the core team, the site owner, and the plugin/theme author. Then it will automatically assess the risks involved, and make the decision whether or not to roll-back to the last version or not.

That would take a lot of work on the part of the core and plugin devs. But I think it would be totally worth it, and probably necessary to improve user confidence in the update process.