A world with no lifestream has nothing to save it from a cataclysm.

[His arms stretch apart in a gesture, while his eyes trail towards the sky. Vincent can probably figure out what he means. If he held the black materia, nothing would stop meteor. No intervention from the lifestream to push it away.]

Perhaps I shall continue on the path my mother once took long ago. Take this world to create a shining new future free from the parasites currently desecrating it's soil.

My point is --

[His eyes suddenly drop back down towards Vincent.]

Nothing here can stop that from happening.