Drexler's closed a couple of years ago when Clyde's mom decided she wanted to retire. A lot of the other places mentioned I don't think have been around for awhile.
I've had many a brisket sammich from John's Country Store in Egypt (had a buddy with a family farm down the road a couple of miles -- hunted there all through high school and college). I don't know if they still do it, but they did a couple of years ago. It was first-rate stuff.
Cool article--thanks for the link. This is probably preaching to the choir on this board, but I highly recommend Robb Walsh's books on Texas barbecue and Tex-Mex. They have great recipes, as well as fascinating historical information and photos.