If Jon can't or won't try to help his voice it probably should be the last concert. I say can't because at this point maybe not much can be done? I say won't because obviously everybody on here knows Jon's voice has not be great for years. If I were a professional singer and my voice even started to go off just a bit I would be trying to get help immediately. Jon either hasn't gotten help or the help he has gotten just hasn't been all that good