I suspect strongly that this is going to be the future. I can only really look at this through the prism of a guy who tends to play small clubs in the UK. I also believe recent events in Manchester are only going to reinforce the idea (among those with a more mature brain) that a crowd is a thing to avoid.
It's a tricky one. We could be very principled and sit at home as our venues gradually fold (the numbers of people will not be enough to sustain the place) or we all try and swim together. This is, indeed, crystal ball stuff but I do believe that the number of playing opportunities are going to shrink. Rather like the jobs market. Places are closing and so the there are fewer jobs and more people trying to fill those that are available. That itself is going to push down band fees as a result of the change in the supply/demand curve.
For free? If my back can be scratched later on (if you trust the venue to honour a gentleman's agreement) then I would. I wonder how many venues (pubs especially) have built up that kind of goodwill?
In general, my maxim is always be as loyal to your employer as they would be to you.