You have to remember, Sega released a version of Vanquish on PC. Think about why that was done. Think about it.Vanquish 2?
Vanquish 2!?
That's not a thing. it will never be a thing.
As everyone knows the universe is a cold, hostile and, at best, uncaring place. All justice and beauty in the universe is the figment of mortal man reaching so a single string of comfort in his existence when we know there is none. Equally, if there is one universal rule in video games it's that games that don't sell get not sequels, no matter how good they are. For there to be such a thing as Vanquish sequel there would have to be some kind of benevolent force out there extending its divine hand out, it's god hand, if you will, exacting justice where there once was none.