It will be interesting to see how the malls pan out.
A part of me thinks that there is maybe some long term issues with the malls that may eventually require
MA intervention to protect the players investment.
Basically unless you intend to recoup your investment by selling the shops for 20K Peds or more, you will be relying on the tax income from items selling.
You effectively are giving control of your income to other players. Some of these players will run shops for a while and then move on. When that happens they either sell the deed, or in many cases dump it in cold storage in the hope that it goes up in price at a later date. When that happens Mall Owner loses tax income because the shop shuts down when you don't pay the rental cost to
MA.
A more evil player, could also buy up shops in mall and deliberately not use them. Effectively denying the Mall Owner income by starving their tax revenue.