If you add a Bouncy Ball to this concept you can do away with the ConductorInteresting concept. I guess the optimum would be a "music stand" where the actual stand is just replaced by a screen. In turn, these could be linked to a central computer (perhaps controlled by the band librarian) with everything in order, and no more issues with missing parts or misfiled items. This could be done in "real time" so that the screen only needs to store 1 piece at a time, or on a whole concert basis. I think there needs to be some sort of adaption so that "pencil marks" can be added (and remembered) but can also be deleted as needed.
Cost will have a big bearing and for most on here it will probably be prohibitive for a long time - British brass band players are generally amateur, rather than being paid for playing - so the cost would have to be found by the band.
But I can see a time when it will come - not sure about in my life time (I'm a middle aged player) but I'm sure my son will see this in his lifetime