Those still running version 1.0.0 and 1.0.1 are advised to update soon. Next version (1.0.4) and those who build from the current source won't be able to connect to you, or rather, you won't be able to connect to the majority of active nodes.
They have to upgrade their wallets if don't want to stay on wrong chains and got massively continous orphan blocked found.
Yes, that's the idea. There is still some time though. Just giving a notice so there is no surprise later on.