Yeah, it might seem weird but Lordareon is too small for a semi-decently sized NRP campaign.
Forget WC3, you'd struggle to play WC2 style events on it.
I can make an alternate suggestion, though. What if we expand the scope to the entirety of the Eastern Kingdoms and to make things interesting we take an alternate ending to WC2 where neither side won and the Orcs still hold Arathi and Stormwind? WC3 events still kick in with the Scourge's appearance but things would be more diverse and chaotic.
I personally think Lordareon is the perfect size for the RP. The current map holds the (pre 3rd war) Kingdoms of: Lordaeron, Stromguarde, Gilneas, Dalaran, Amani Empire, half of Quel'thalas, Frostwolf Clan and the Dwarves of Aerie Peak. After factoring in lost territory due to the scourge it's a good size area to slowly expand before butting heads with one another.
I guess it all comes down to how many people were willing to join the rp. I had planned for most of the plot to revolve around the conflict with the Scourge, and that wouldn't really be possible south of Silverpine. I am willing to lengthen the map if there's a great demand for it.