If UBI is introduced to some countries, then it will be the end of those countries, as UBI is pure communism. If UBI is introduced to all countries, then it will be the end of the world.

If AI reduce some of the work in some sectors, then people will have to move to another sectors, change their specialization. If they don't do it, they should die. In nature, those not adapted perish. It's normal and it has to happen. If you fight against this universal law you will lose. You just can't fight against it, no matter how clever you think you are. You will be punished by nature by collapsing all the race. And perhaps the few that survived can recreate the world again, but who knows.