Pointless, maybe, but it would help tie some things up. I am pained to see that VotS will be ending, but a new start would be good.

My recommendation for an ending that concludes in unity is something that threatens the entire fate of our races at the hand at one super-powerful race, one that even Chaos would realize that it needs to fight off. Maybe something that wants to trigger a doomsday weapon (A la the Halo Rings), or some kind of virulent and cancerous entity that attacks worlds and grows, like the Reapers. 

Or maybe something completely original and unheard of, who knows.