I've had three wheels fail by cracking through the brake track due to wear. So far, the failures have been pretty benign. I was riding along and noticed a "thump, thump, thump" when I applied the brakes. Inspection showed a small section of the rim had bulged out and was hitting the pad. The cracks and the bulged section were small enough that the tube didn't fail and I was able to ride the bike home, but rather cautiously.
I wouldn't use my experience as a guide and I know I've been lucky. You may not be.