Frankly I'd be fine with simply stepping up the game against tax evasion. If corporations paid their fair share to begin with, we'd have a lot less issues like this to begin with.
In terms of concretely for this year (and not being a fiscal expert, just some rando on the web, as I'm sure you're aware) I see governments giving out help to people/companies in need, based on a comparison of current incomes/profits and last year's income in the same month. Not that that's perfect, but if it is workable, I don't see why this couldn't be generalized to the case where companies (or people, but that's probably a fringe) make significantly more profit now than last year around this time. Given the broad economic problems, that should separate out the winners of the crisis quite neatly.
Paired with possibility for individual recourse, that should bring in some decent tax revenue and leave room for people who feel their increase in earnings is nothing to do with the pandemic. Of course, those people would have to make the effort to defend that case, and might also stand in the "court" of public opinion as a result.
Apart from that, I don't see why it seems a foregone conclusion that e.g. rent will have to be paid in full. That basically says "we guarantee that whatever happens, people who are well enough off to own more property than they inhabit themselves will not bear the consequences." I don't think as a hard-and-fast rule that's fair either. Because the inversion of that is "whatever happens, we'll have it be paid by those who have the least already."
Your state-capitalism solution punishes the firms which successfully adapted, to rescue the firms which were incapable of adapting. This creates substantial moral hazard and is a key reason why state-managed capitalism sees less innovation, and is instead plagued by inefficient zombie firms which make their profits off bailout funds instead of in the market. The scheme rewards the entrenched interests for running fragile operations, while shutting out new competitors who might be better or more resilient.
Mind you, these zombie firms proliferated in Europe after the 2007 crisis, so this is really nothing new. And the good news is that when you do such a thing, you can avoid more disruption. But the bad news is that doesn't leave the economy more resilient when you're done: it leaves it more fragile. In the years ahead, if Europe is further tested by crisis, we may see the real price that her people have paid, and it might very well fall hardest on those who can least afford it.
> Your state-capitalism solution punishes the firms which successfully adapted
That would be true, iff the taxes canceled the gains out entirely. Which... I never said. But that always seems to be the expectation when someone proposes to tax wealthy people. Pandemic or not, I never argue for an effective tax rate close to 100%. But I don't have to. I can argue for the effective tax rates being much, much higher than they are currently, and still stay comfortably far away from 100%. So the incentive to gain more would still be there, it just wouldn't be as strong. Not-so-incidentally, I think that would actually be a good thing.
In terms of concretely for this year (and not being a fiscal expert, just some rando on the web, as I'm sure you're aware) I see governments giving out help to people/companies in need, based on a comparison of current incomes/profits and last year's income in the same month. Not that that's perfect, but if it is workable, I don't see why this couldn't be generalized to the case where companies (or people, but that's probably a fringe) make significantly more profit now than last year around this time. Given the broad economic problems, that should separate out the winners of the crisis quite neatly. Paired with possibility for individual recourse, that should bring in some decent tax revenue and leave room for people who feel their increase in earnings is nothing to do with the pandemic. Of course, those people would have to make the effort to defend that case, and might also stand in the "court" of public opinion as a result.
Apart from that, I don't see why it seems a foregone conclusion that e.g. rent will have to be paid in full. That basically says "we guarantee that whatever happens, people who are well enough off to own more property than they inhabit themselves will not bear the consequences." I don't think as a hard-and-fast rule that's fair either. Because the inversion of that is "whatever happens, we'll have it be paid by those who have the least already."