that would ruin TR if Meowth did evolve. Noone would jump from above and shout "that's right!!" anymore. And besides, TR looks goofy with Meowth around....that way i like it. I just wish Meowth learned more attacks though.
it will never happen. the pokemon decides to evolve or not to evolve. maybe meowth doesnt want to evolve coz he likes standing on two feet and having a gold thing on its head, which makes him happy.