The big question is How? Hungary had no land border with a NATO country the only option would have been to invade neutral Austria, which would have undermined NATO's justification for intervening in Hungary. The Austrians wouldn't have taken it lying down, they wouldn't have been able to stop NATO passing through but they would have made life difficult.
And of course this will likely cause WW3 which will go nuclear very quickly, the Soviets had plenty of tactical nukes but they didn't have a strategic capability anything like as powerful as SAC so while Europe, and Germany in particular, is going to be a nuclear firestorm, CONUS will be relatively safe. In contrast the USSR will see its major cities vaporised in the space of a few days so NATO will emerge victorious but millions will be dead.