Observations:

In one session I go to, most non playing customers used the other bar. I don't know what that bars is doing now but the ban does not seem to have affected one or two drifting in to the music room.

In terms of non-playing customers, the other has been quieter on the weeks I've been there. As long as the pub feels it is getting enough custom (and I think it is), I view this as a good thing as noise levels were high in there.

In terms of players at these sessions, there have been no changes. Noone has either stopped playing or started coming as a result of the ban. Except...

I've stopped going to the local folk club as a result of the ban (in terms of stress I feel vs what I get out of it, it was tight before but this tipped the balance and I no longer consider it worth my while) and have swapped it for an extra session. As far as I know, that has been the only change there in terms of regular singers/players. I'm not aware of (and I do go there at least one a week for the last 1/2 hr and a game of pool and have chatted about the club) of changes in other customer levels on the folk night.

Re the opening question. I've heard nothing along these lines but it wouldn't surprise me that some pubs are more interested in putting on music (and probably open to consider anything) as a result of the ban.

Whether such efforts would keep a pub viable long term might be another question but I certainly can not see a group of folkies perhaps only once a week and (I know there are exceptions but...) generally not drinking a lot achieving much. I think, in many cases before the ban, we have needed the rest of the week customers to keep the pub open for our folk nights.