I suppose they could find a way to insert audience members that aren't actually there, whether it's mannequins, superimposing, whatever and add in simulated audience noise, but unless they can get to where it looks really good I'm not sure CBS and Fremantle would want to go that way when they can just show reruns.
I could see reruns for a longer than normal time until they are allowed to tape with something like 100, maybe 50-75 audience members. Perhaps if they're allowed to until regular tapings can resume they would do 1-2 specials with a more limited audience with only local contestants including a salute to front line, first responders, and other essential workers with the matching winnings going to charity like in the Price at Night specials before Christmas and with RuPaul last week.