Yes, Valve will not allow this to happen again. They have allowed this to one CS:GO event, yes, only staffs, players and teams were inside the event and there were no fans because of the circumstances that they've faced.
With the said new mechanics about the regionals, it's okay to conduct online matches and no problem with those casters and broadcasts because there are a lot of companies that do cover it. But the championship? if you mean about major or the biggest event for Dota 2 which is TI, I think it they will just move the date.
I hope that by the time of the TI the virus epidemic will be over and VALVE will not have to choose between moving the championship and holding it without spectators.
Although I stopped playing games a long time ago, I continue to watch major gaming Championships such as TI.
If you have been a player since Dota(1) old days, you'll still a fan of it and even wanting to watch newer players and teams compete with each other. The hype that it's getting because of the yearly increase for the prize pool especially for the champions makes everyone wanting to watch the tournament.
We don't have any other wish but to see this pandemic stop and be gone as soon as possible.