Proposed Nasus changes
I think Nasus needs a small change to his play style, an well this may make him a solo que monster, in reality it wouldn't change the amount of DMG Q will be able to do overall.
My suggestion is to take the stacking component off Q, and move it to his passive. Giving him more dmg on Q, for all things he kills with any attack. Yes the stacks per kill would have to be reduced, but he could be able to have a lane presences using Q and E to actually fight back.