As far as I know, this hasn't really been a problem for any Bitcoin forks but if it ever becomes a problem for Bitcoin 2, there are solutions for such. For example in such a case we could consider locking any unclaimed BTC2 from the fork, thus lowering the supply. (By checking whether or not they have been moved in some way since the earliest blocks of Bitcoin 2. Such as by staking them or by transferring them.) We can already start discussing how you guys would feel about such a move if one day it would be wanted by the community as it is not the kind of decision that the developers should do on their own. The easiest way is to lock them by code from using the BTC2 that they have, based on the public addresses. Such a lock could technically be undone later but if we decide to do it in the first place, it is very unlikely that we would want to undo it.