I'm skeptical of this happening. Right now it's easy to upgrade while the community is small and people download their client from one source.

But once everybody is running different flavours of Bitcoin, network-wide upgrades are not a solution.

Take a look at ipv4 and ipv6 today. The internet runs slower, less secure and is running out of addresses but nobody upgrades. Eventhough there's been many years to enable ipv6 and the running out of ipv4 addresses was well predicted in advance.