Peal ringing decline That's a very good answer. I have been thinking about how to answer my own question since asking it.
It is difficult to understand the attraction of peal ringing until you've rung quite a few. The best and most challenging ringing I do is in peals, because most of the best ringers I ring with also ring peals for the same reason. Peal ringing does improve the ringing of most of those who do it. That said, there are established bands who enjoy quarter peal ringing for the same reason - because they get good ringing. I was at AJB's funeral on Tuesday and he loved his QP ringing and rang about 3500. So that was probably when he got his best ringing.
An aspect of peal ringing that has not yet been mentioned is the exploration of composition that is not possible in smaller lengths, but this is particularly for more difficult stuff and on more bells. There isn't really a quarter peal equivalent of the challenge and beauty of ringing 147 minor, 23 spliced, Cyclic Spliced Maximus, and the ringing tends to get better the harder you make it because the ringers are more experienced. The analogy with Test Cricket over shorter forms of the game was good, but I would also draw an analogy with the Symphony over shorter pieces of music - a Symphony gives you time and scope to explore far more. 3000 changes would probably be enough though, and although I have put forward the idea of 3000 being a good target, I have yet to had the courage to organise one.
So on to whether the drop in peal ringing matters or not. At the moment there is a body of ringers ringing a lot of peals together who have retired early in good health and with good pensions. That is the group who are particularly causing there to be a greater concentration of peals rung by a smaller number of ringers. That will work its way out of the system and the peal numbers will drop, but that in itself will not make much difference because that ringing is not putting much back (generally). It is people who like ringing together doing so because they can. That generation will not happen again until something fundamental changes.
We have definitely passed 'peak peal' - future generations are unlikely to ring as many, but it I don't think it will fall away catastrophically, particularly because the children of ringers will be brought up wanting to do it and they will encourage others.