He's doing quite well and I'm glad to see him again but I couldn't help but notice after the game that he has an insane amount of sustain options now.
Thanks to Conqueror and the buffed Bloodline Rune, Nasus scales up to 36% lifesteal with an additional 10% of all damage he does. With a red elixir it's another 15% of all physical damage. And of course this is all amped by 30% when he has Spirit Visage, a core item. I've played it, and the healing is quite insane.
If Nasus does need a nerf, and I expect he will soon since he's performing so well in soloQ and his few meta counters are seeing both indirect and direct nerfs, I think the best thing to hit would be his passive lifesteal bonus, just to address it in the light of how much sustain he is stacking right now.