Hopefully, Dave Grohl accepts the invitation!
The Perth Symphony Orchestra is going to do a special performance on September 28th of UNPLUGGED: Nirvana Reimagined and they've extended an invitation to Dave Grohl to join them in the video below. It is in Australia, which isn't optimal for travel from the United States, but, Dave certainly could make it happen.
Even if he doesn't, it still looks like a phenomenal show and the Perth Symphony Orchestra should think about bringing it here to the U.S. I guarantee they'd have a ton of people out for every performance!