I don't think Xykon has the right mentality to suffer a complete villianous breakdown; after all, we saw it come pretty close to what you are describing back in Azure city, and all we really got was a "we gave it our best shot, so much for that".

And Xykon got seriously angry at V and O-Chul when they broke in/out of his tower, but remains focused as ever.
Even if every gate is destroyed and/or kept out of his hands, what's 20 years down the tube to an immortal lich?

As satisfying as it might be, I think the best we're going to get is perhaps an "Oh [poop]!" moment with Xykon reduced to nothing but a skull as his phylactory is smashed.