They're in the process of removing the concrete right now.

The demolition of the Joe Louis Arena has been underway for a few months now and should be done by the end of next year. The company who has been hired to take down the iconic building has made it VERY clear that it will NOT be a Silverdome-esque implosion; they're demolishing the building from the inside out.

https://www.facebook.com/search/top/?q=joe%20louis%20arena&epa=SEARCH_BOX

As of now, the locker rooms are gone, the Olympia Room is gone, and the main floor is a pile of rubble.

Outer chunks of the building will start being removed in the second week of June, so if that's what you're waiting for, it's coming.