(For those unfamiliar: there's a tired annual joke about DEF CON being cancelled, the scene's equivalent of trying to sell the freshmen elevator passes, so expect lots of jokes about how the conference hasn't been cancelled. It has, predictably, been in fact cancelled this year.)
Along with Black Hat (the "professional" version of Defcon) and B-Sides Las Vegas, this is "security summer camp", the weeks at the end of July and beginning of August. None of these events are likely to occur on-site this year.
Later
And, on cue, in-person Black Hat is cancelled as well:
https://twitter.com/BlackHatEvents/status/125883283428810752...
Black Hat is still going to happen virtually (we just finished selecting talks).