I think Multiplayer will work best if people have to specialize, i.e. classes in other MMO's. Specializations could be Residential, Commercial, Industry, Entertainment, Infrastructure, Environmental, Parks & Recreational and so on. That way we are all dependent on each other. Also, pay to play will fail miserably if MC does not have a dedicated team to regularly add features and insentives to the game. Not sure what insentives will keep me paying though, maybe reaching certain milestones will get you titles and new buildings/structures that are functional. For example, if I specialize in Environmental I would collect trash and after a certain amount I would unlock a "Landfill Gas collection system" that will allow me to convert Methane to energy then sell the Electricity.
I agree that taking away features in single player to get people to play in multiplayer is a very BAD idea. Single player should be a sandbox type game giving the player ALL available features. Cooperation and entrepeneurship should be the driving force of Multiplayer. Again regular updates and adding features will be KEY to pay to play multiplayer. If they can make this work It will open up the MMO market to bigger and better ideas of what an MMO can be, it shouldn't be restricted to the RPG genre. I wish MC best of luck on this endeavor. I will be a paying customer If they can manage to pull this off.