The he really is a huge threat to whatever planet is unfortunate enough to have him touch down on, without any friendly Kaiju. Yep, doomed pretty much. Earth would be infested pretty quickly, if it wasn't for it's protectors. Each one of them going to need to be available, the next time he shows up. It's gonna take a team to beat this guy, quite clearly..
He has consumed 11 billion life-bearing planets, and there was a prophecy fortelling an event called Convergence, where ALL remaining Kaiju throw aside their rivalries for the greater good and team up to stop the Necromancer. Godzilla manages to destroy him, but Earth is still heavily damaged; the death toll is expected to reach millions.