Four concepts on one platform isn't that a hard job for the dev's? What if the system will crash because of knotting of the features of the platform? How can you will assist and cater such kind of problem in the system?, it is possible actually because of system overload and overly using of users in the same time.
I think it will be sufficient if they will provide a very powerful server or even multiple server computers for their project. Well, I am sure that they will also have maintenance and updating on their platforms. Also, this does not necessarily mean that it runs on one platform alone, clicking your desired service or product from Smart City Eco platforms may redirect you to another website dedicated for that particular service or platform. For example online shop. This will surely have a separate interface for choosing products available.