Ah this one's a tough one, I loved the Foo Fighters when I was a kid, one of my first big concerts was their 2007 Wembley show when I was 18. I haven't enjoyed their music since probably about The Pretender but I don't think you can argue they're not a good band, one of the few palatable "stadium level" rock acts. Genuinely sorry to see he's died, at a very young age too.
They'll definitely cancel their shows for the next twelve months or so, and may even go on a long hiatus, but I take a different tack on it from most of you in that I don't think it will be the end of the band. It's easy to forget that despite all of the other musicians being incredibly important to Grohl, and by all accounts his good friends, the actual direction of the music is, and always has been, his. That drive to create music won't disappear, and I actually think he'll believe it a disservice to Hawkins' memory to wrap up the band.