The thing I've noticed is that even dying downtowns want insane amounts of rent; I think you have to be able to buy the building to make it work.
However, that's not as unrealistic as it may seem, because the city itself often owns a decent amount of downtown, and can make a deal.
If the only way to be successful is to start by buying multiple downtown locations outright I think we know why the downtown is empty. Nobody is going to do that to open a shop. Not even the mega chains are usually buying anything.
It's really baffling that even in the shittiest areas rents or property prices are insane. It seems the capital owners just don't care or don't lose enough money to care. They should be expropriated. Of course that won't happen.