Nothing even remotely close to a persistent MMO-like multiplayer.
I can't really see that turning in anything else than a big mess to manage.
Oh, it's easy!
First, you allow it to happen with restrictions set by players.
Second, you watch an economy evolve.
Third, you watch hackers destroy that economy.
Fourth, you ban ten thousand accounts for hacking.
Fifth, you ban another ten thousand accounts for hacking and complaining about the bans they received on their prior accounts.
Sixth, you keep banning people while watching in horror as hackers completely take over and ruin your game despite your best efforts.
Seventh, you make your next game into an always-online game in a hope being able to ban people from playing at all keeps the hacking under control.
See? Easy!