Hardware bans were discussed a few times on forums, though they are still not implemented yet, and there is no information from devs are they in favor of that idea or not.
Though as always, the question comes out: who's gonna code it? Who's gonna spend his free time for it?
And implementation of unique hardware ID will be tricky, since it's very close to software license protection systems, which are constantly under attack by pirates.
As an alternative, it's possible to link MBII Launcher to some social network, like Facebook or vk, via
OAuth technology.
Those social networks send confirmation SMS to each newly registered user, not allowing to use same phone number to be used twice. That's a pretty good protection, and MBII team wouldn't have to implement sending SMS on their own.