If we have already updated to 8.1 and we are just waiting for the Mac jailbreak, why would we be locked out if 8.1.1 drops before the jailbreak? Just don't update to 8.1.1...
It's not guaranteed you'll be locked out, however, if something goes wrong on your first attempt to JB..and you have to restore.. you are screwed. You will only be able to restore to 8.1.1. It's best to get it done now and get it working stable.