Its more of a problem security wise. There is now guaranteed hardware out there that can produce more than 50% of the hash power but its currently not "working" for bitcoin. This in theory could mean someone is secretly mining a longer chain which could later be made public and "reverse" the other chain.
This is very very unlikely to be the case because the "missing hashpower" is likely being moved to other locations and that is the reason why it is not running.
The profits will last until new datacenters are set up outside of China. It's a slow process to do that, hashrate might not return to its peak value for 6+ months.
The increased profits will continue until everyone who was displaced from China can find a new home, but this isn't going to be a quick process, Bitcoin requires enough datacenter space that all the Bitcoin-ready datacenters outside of China are already full!
Miners have no interest in simply giving up on profitable mining gear.