I was at the Atlanta show last summer. It was better than I expected. I went just so I could see Brian Wilson, who is one of my music heroes.
Britney Spears by far. She has become a parody of herself. Christine aguilera is skirting the edge. I think lady gaga based her image as a parody of the teen idol to begin with, so im really looking forward to what a parody of a parody will look like.
Val Kilmer definitely seemed to follow the Marlon Brando model for transitioning from hunky, respected actor to XXL, difficult oddball.
I’ll throw Nicolas Cage out there, only for the quantity of crap movies he appears in, apparently in an effort to fund his lifestyle.
I’ll also suggest any number of washed-up action-movie actors (Stallone, Schwarzenegger, Seagal, Van Damme, etc.)
However, now that I think about it, I’m not sure that any of them really meet the OP’s criterion of “still have a legion of loyal fans”.
I was wondering about Rod Stewart and Crosby-Stills-Nash. But they have been accused of being tacky parodies for 30 years
I know some people who say the new/upcoming Clash box set is a violation of everything The Only Group That Matters once stood for.
Yeah, I don’t see that The Who as they currently exist are any tackier than any other classic rock group that’s still performing. They’re not the same as they used to be, but they’re not wearing sequined jumpsuits either and I don’t think the lyrics to ONE song mean they’re obligated to retire while similarly elderly rock artists keep touring.
I saw The Who several times when they regrouped in the '90s and then again about six years ago, and was rather surprised to see that they’ve attracted a sizable young audience. I was a teenager in the '90s and when I saw The Who then I didn’t notice a lot of other people in the crowd who looked around my age. But at the more recent concert there seemed to be a LOT of teenagers. I’m sure today’s teens are aware that The Who is an old band that hasn’t recorded much in the past 30 years or so, but they may actually be seen as less of a “no one listens to them, that’s old people music” act today than they were when I was a teenager.
C’mon, how is the answer not Ozzy Osborne?
You’re assuming he didn’t act like this 30 years ago. From bits and pieces I hear from interviews, he was fried from drugs by the 80’s.
Kenny Rogers.
He does sound as good as ever. 
I like this answer. Is he still performing much?
Yes, but he could actually perform in the 80’s. I saw him live seven or eight years ago and was hobbling around like an old man and screwing up the lyrics of War Pigs.
The CSI factor?
I appreciate the joke, but Dylan DOESN’T sound as good as ever.
Dylan always had an unconventional voice, and yet, somehow it used to work. He was almost always the best interpreter of his own songs. Better singers than Dylan regularly covered Dylan’s songs, but they rarely improved them. NOBODY could have sung “Tangled Up in Blue” better than Dylan did.
But today, he usually sounds HORRIBLE- not compared to conventional singers, but compared to his old self.
That said, he’s still writing good songs. Today, he NEEDS the equivalent of the Byrds or Peter, Paul and Mary to perform his songs, and make them listenable.
I was worried about Robert DeNiro falling into this category when he did a third “Meet the Parents.”
Nice. I was gonna go with the Hair Metal bands out on nostalgia tours, but I think you’re right. Alice Cooper seems to be more in on the show. Elton John, too, IMHO.
Axl Rose.
It’s really no contest there. Seriously.
Oooo. Also nice. He and Ozzy are hard to beat.
Whitney Houston - her decline into sheer irrelevance was quite some fall. She really did become painful to watch, forgetting words and missing notes by entire time zones.
Axl Rose wasn’t a punchline of late night comics. Ozzy was. That’s a whole different level. You’re not a modern-day Elvis if you aren’t a public punchline.
Whitney Houston comes close because she too turned her life into a reality show, but she’d dead. Ted Nugent comes close because he’s publicly insane. There can’t be many more who are instantly understandable as punchlines. Dylan doesn’t count as long as he keeps putting out acclaimed albums. Elvis Costello just recorded with The Roots and everybody’s raving.
Madonna’s a weird case because she’s mocked for not turning into a fat insane person. You can’t win.