Well, only if it uses direct Google Android and updates when Google updates. If it's it own, special "take" on Android (like Samsung and nearly EVERY other manufacturer), it's more like you're stuck with whatever OS updates the manufacturer provides...if ever.If it's running Android, well they are stuck with whatever OS updates Google wants to provide. You can only go so far without making your own OS.
Samsung's OS update strategy, at least in the past, seems to be "hey, just buy the latest phone, it's got the updates on that"