One thing that is clear from this article is that every device offered as a solution to this problem is different...
I think that days set aside say on Salisbury Plain to burn off the out of date flares would be very well attended by those wanting to find out how they actually work in practice.
Not sure anyone had yet developed an electric flare that will shoot up to 2,000 feet for all to see from 10's of miles away, as it drifts slowly downwards. Parachute flares for me every time.
I'd certainly take my bag of old rockets along.
The trouble is, nobody's going to want to take responsibility for such an event in case some idiot tries to sue them after burning himself with his own flares.
Pete