Could a developer tear it down along with other functionally obsolete properties to make a strip mall or something of that sort?

Investors looking for cash flow will be tempted to look at old, non-conforming, functionally obsolete C and D class properties.

As far as obsolete layouts or foundation problems...etc., From the day that I started this business I told myself that every property I get in my truck to look at gets an offer made on it asap. 

The old HML's who would supply rehab funds for no money down are obsolete now as they have lost so much $ they have gone out of business.

When a tennant moves in they will call for new service and the provider will come to tone the lines and figure out what is what. 80% of the wireing on the building is probabely obsolete any way, not may people get hard-line telephone any way.If the wires are coaxial cable (used for "cable") then you can remove them all if the building is vacant because the provider will run new for new service.

Maybe functionally obsolete?

These systems are mostly obsolete, except for heating swimming pools usually in commercial applications and there aren’t many installers left in business and even fewer installers that like to work on rehabbing older systems.

The stuff you have to watch out for are the [usually] older homes that have funky additions added on, and now they are just obsolete mazes.

Does this mean rentals are obsolete in this area?

And it's not about attracting more business, it's about being in the know, not obsolete.