I'd argue most of those malls ALREADY have many of those things.
Many malls are pushing 50-75 shops, so that's a LOT of electric and telco already present as well as UPS/FedEx/USPS drop points.
Malls are often near highways which is where most of the fibre got laid so it's easy to add.
Many malls already have basic backup generators (plus natural gas and such already ran) in place for stores, not to data center standards, but in place.
These shops aren't "that big" that they need major renovation into data centers, they'r plain brick boxes right now. They are more the size of a telecom CO office. It's only now that everybody is Blade servers + SAN that it would even be practical to use the space.. again because they are SMALL enough not to be a major drain on power resources like the major centers are. I understand your point, as I work for a steel melting mill and many data centers are starting to catch up with OUR power usage.
as far as security, the best security is often in plain sight. most of the abandon mall properties I see (at still used malls) are kept up on the surface pretty well. There's plenty of security already for the mall (to watch for parking lot vandals and robbers, etc)and these would not have any foot traffic to speak of.