The Greek word that has been translated "all" means "all parts of" as in not just the 12,000 from the tribe of Judah (Jews) but representatives (12,000 of each) of "all" of Isreal will be saved. It is in reference to the separation of Israel.
so you think the 144,000 is a literal number also, oh boy. dispensationalism with a dash of Jehovah witnesses thrown in for good measure.