Sadly, since the Carrier delivers the update, they cater to those on contracts, so the unlocked variants will get theirs last. It used to be that unlocked devices pointed to Samsung for the updates, so got them first, but now that setting gets changes when you insert a sim, so you go to your Carriers servers.
Nothing changes. If you change to a different carrier's sim, then it will provision your device to use the new carriers servers. This is not a setting that gets rolled back, so you will never get back to using the Samsung update servers. Even if you could go in and change the server back to the correct Samsung server, it would change back the moment you try to access internet or phone services.
I guess Nothing changes is slightly incorrect as you would lose internet and phone services other than Wi-Fi connected ones.
