I remember passing by an open Blockbusters a few months ago and being shocked that it was still around.
I feel that way about Radio Shack. They're everywhere and yet I haven't been in one or seen a commercial for them in years.
Still, Blockbuster's demise has left a tiny hole in the market for people who want to rent a movie that isn't a new release or something fairly famous and old. If the streaming service you subscribe to doesn't offer it, your only option is pretty much to buy it outright.
Netflix mail-in still exists, though in terms of getting it the same day, yeah that's a valid point. However just as independent record stores have managed to hang on despite the end of the big chains, a few mom and pop video rental places have still stuck around as well and will no doubt be around quite a bit longer after the end of Blockbuster.