The only way it can go badly is if they try to use force against them. Then yes it will be a very bad day for the invaders..
And the Left media will be there photographing every illegal and every injury and drop of blood to broadcast the the world painting Trump and the right as tyrants shooting at and or strong arming women and children. Fair and honest reporting is the last thing we'll get.
The Left media needs to be neutered because in it's present form, it amounts to a clear and present threat to national security.
Perhaps the government should take over the offices of ABC, NBC, CNN, MSNCB and CBS in the name of National Security otherwise, they'll keep encouraging these caravans and hostile actions towards America.