Overall vacancy for the entire metro has been hovering around 20-25% for years now, and downtown even higher at around 30%. Overall Class A vacancy is sitting at 15-20%, as well. The office market downtown, and in the entire metro, has been soft for many years, now, and it's not going to get much better. Heck, Redico is having time finding tenants the remaining space in the speculative, 10-story One Kennedy on Campus Martius, with most of the current tenants being pulled from other downtown buildings.
I seriously doubt it's going to be tall, but I really couldn't care less as long as its a good design that fills a block. I've said it before, but I expect it to be built much like the massing of Compuware, and at the max, a height of 300 feet or so. "Big", I doubt, can be equated to "tall". The big announcement is big because it's supposed to include multiple announcements. My feeling it that it has something to do with the new JLA, too, and the renovation of the UA.
Where the trees are the right height