That's too bad about Johnny Winter. I saw him about seven years ago and it was one of the best shows I have seen, and I have seen many, including SRV,Clapton,BB King ect.
Another great blues guitarist still touring is Elvin Bishop. He was a founding member of the Paul Butterfield blues band and left after a few albums for a long and successful solo career. An enthusiastic showman, his down home guitar style is more laid back than the other artists mentioned here.
Also, check out Deborah Coleman. One of the best of a newer generation of blues guitarist.