Circle Centre Mall in Indianapolis has about 12 million annual visitors. To support that type of traffic would require a vastly greater population than presently exists downtown. I'd expect the same is true of Cincinnati. Even if the population of downtown tripled, it probably wouldn't make a dent in Tower Place's problems. In Indy, the Mall benefits from being directly attached to the convention center and only conventioneers and other special events attendees are keeping it afloat. I expect reports of the same types of troubles there in the not too distant future as the mall's operator - Simon company - also owns the Fashion Mall and has elected to steer destination retailers like Tiffany's and Saks there instead of downtown. Circle Centre has a very uninspired retail mix and if the convention business suffered at all, the mall would be in trouble. With Nordstrom opening a northside store this year, I'd consider the future of that company's Circle Center store in doubt.
I wouldn't be planning on new residents to bail out Tower Place or downtown retail generally any time soon. Chain restaurants like McCormick and Schmick will no doubt thrive however, just as they have in Indy and elsewhere.