Doesn't matter. The end of mechs is the end of the product, since you can't make anything more intriguing and evocative than them.

You can raise your finger up high and say "erm what if you blew them up with a big bomb from a billion miles away?" and all you've done is blow up the interest in the franchise. You've no game left. The drones and tanks and battleships in space will kneel and bow their heads because they know that they can't kill the mech without killing themselves.