There's a development sign now on a building directly east of 590 Atlantic, and across Flatbush from Barclays (those bollards are for the arena & subway entrance). There's a pop-up Puma shop next to that, and a Shake Shack, and the rest of the block fronting the arena has been demolished. The building with the development sign is at Pacific & Flatbush, and as I said before, I'm guessing someone is assembling the sites for something probably retail/entertainment, but I don't think anything tall can be built here because of all the brownstones also on the block.
