Greetings from McAfee.
As far we know, if supplier changes and you still have a McAfee subscription, true key will be working fine. So you don't have to worry about it and also we would request you to export all your password and save it in the backend to avoid misses at time of migration.
1) can the account still run or is there a way to transfer over to a free/ cheap/ paid for account - True Key will work as expected
2) what will happen on 1st April - Account will be migrated from BT to other supplier
3) any other options? - True Key will be fine
Ganesh Raju R