I can't argue that there aren't empty storefronts, and I'm (very) happy that at least one company is investing in the neighborhood. I just think the dress shops (and home furnishings and knick-knack shops) have limited appeal. Plus, a dress shop doesn't have the type of traffic that some other types of stores have (mostly, restaurants, but you can't have those, everywhere). Real estate agencies are bad for this reason, as are dental offices and law offices.
The five on the "most desirable" are being filled, shortly, FYI, if by "desirable" you mean my area. Stephi's on Tremont is going into Garden of Eden, Bostonian Market is being renovated ... actually, that's it. Who knows what will happen to the photo shop (maybe they can start selling fake IDs like the other shop ...).
The empty storefronts near Cathedral are empty because the owner is stubborn, I think, based on comments he made in the South End News. Looking for rents he can't expect to get. Don't know about Harrison.
Tremont St near where okw is going will be reborn when the commercial spots at 641-643 are done and when the spots at 657-659 are done, both next year.