I mused a year or so ago (oh I think it was actually only 5-6 days, seems like a longer time) that I thought there was a 50% chance the Giro would go on as scheduled, only a 5% chance it was cancelled outright, and the rest of the likelihood was of it being held later. Well, I think I was under-informed of the exponential nature of a pandemic like this, so that was an overestimate of it going on as scheduled. But my basic thinking hasn't changed, and I still think many of the big races could be held later in the year. Just psychologically, it seems reasonable to think that after the next month or so, if things are stabilizing in terms of numbers of cases, restrictions will loosen and what seemed crazy restrictive two weeks ago will seem like a breath of fresh air. Just thinking of somewhere like Italy, when they tried to quarantine Lombardy tons of people just fled to different areas because people aren't used to having their freedoms restricted and they didn't want to start. I would imagine if things stabilize in Italy and hotspots remain quarantined while restrictions are lifted elsewhere, it will work much better than it did initially, as people will respect it because they know what happens if they don't now.
The same thinking goes for sporting events - after nothing for a long time, people will be starving to watch a football match in an empty stadium on TV. Broadcasters and promoters will be itching to make money, especially since lots of people will probably still mostly be advised to stay home and will be looking for a change of pace, which live sports would give (as well as a return of a sense of semi-normalcy). If they want to hold the Tour de France and say nobody is allowed to gather to watch along the route, I feel like people would oblige, or the infrastructure to enforce it would be there in a way it wasn't before, or both.
The biggest problem, though, is that the Tour is, well, a tour. A travelling caravan of riders and 5x as many team support, officials, journalists, etc etc, even aside from the fans. So one day races would be more likely to run earlier than Catalunya or the Giro. Or maybe the Giro would be redesigned to have clusters of stages based out of a single place for 4-5 days at a time, with more rest days to move. Or shortened to 2 weeks (which I would hope against, lest it provide a model for the long-dreaded GT shortening that people in power seem to like). Or maybe the Tour can run on schedule with no crowds. a few of the bigger races can be salvaged in the summer, and the Giro and monuments get pushed to an extended late season after the Worlds. That would be my ideal, but who knows really. I think the psychology of such a move is realistic, but not sure if the logistics are.
I guess the other issue is that cycling is a pretty small fish. Football leagues (with a relatively limited number of athletes running around in an empty stadium), Olympics, Euro 2020 are going to take precedence if anything does, so I suppose if they give up then everyone else might too. Following the resumption of life in China for the new few weeks will be instructive, no doubt.