The main problem on Nos is obviously the big population. This creates a world that is overcrowded so the pvp ganking become untolerable aswell as the lag increases. Both of wich is fixable with a pve server.
If they decide against putting up a PvE server it is just stupid.
Now the developers of Nos isnt stupid so i have full confidence in them making the PvE server happen.
Worst case it will take some time, but it will happen.