Actually and taking into consideration the actual technology, you need a server farm and a communications partner, only to support the server side architecture.
Using FPSC as the main server side engine is completely impossible, no matter the ammount of players you want to use, assuming that mmo means Massive Multiplayer Online, thus, several thousands of users.
And this is only for the number of users, no other considerations taken.
V
I'm pretty sure I know everything. Doubts are something rare in me and I am never wrong, as this signature can prove.