We have an answer now: Signs have appeared in its windows announcing the July opening of a sushi and "modern Japanese izakaya" restaurant called Hiro
I have a call into Blue Ocean Sushi owner A.K., as he is known, to learn of his involvement, if any, in this new venture. In the meantime, if you're wondering what an izakaya is, consult my recent review of Izakaya Ren (2948 Dougherty Ferry Road, Valley Park; 636-825-3737).
Update: (Thursday, June 30, 4:15 p.m.) Stacy Schultz of Sauce Magazine reports that Hiro (not Hir!) is owned by Bernie Lee, who also owns 609 Lounge next-door.