|If magnetic trains are to work, wouldn't friction on the bottom of the train create thermal energy which would destroy the magnetism of the train?
When a magnetically levitated train is operating properly, it doesn't touch the track and experiences no friction. In principle, it shouldn't get hot at all. The magnetic drag effect will warm the track slightly, but that won't matter to the train's magnets. Actually, the train's magnets will almost certainly be superconducting wire coils with currents flowing in them. That type of magnet doesn't depend on the magnetic order of permanent magnets. It's the magnetic order of permanent magnets that is destroyed by heat. An electromagnetic coil will stay magnetic as long as current flows through it, even if it's so hot that it's ready to melt.