I doubt they'll ever attract the R&D budgets that PCPs do, so the best designs of today and recent years aren't likely to be improved on, whilst PCPs are still getting better, and the price gap is reducing.
My Falcon FN12TW is 6 years old now. It only holds air for 40-odd shots, is a single-loader and has no inbuilt pressure gauge, but I still have to say that on any practical measure I can think of, it's better than any of the many springers I owned before it.
I reckon the writing's on the wall for springers, as it was for steam locos and single-cylinder sidevalve motorbikes in the 50s. Sure, there'll be a dedicated, shrinking band of enthusiasts for as long as the things can be kept going, but the rest of the world will move on .
Regards,
MikB
...history... is, indeed, little more than the register of the crimes, follies, and misfortunes of mankind. (Edward Gibbon: Decline and Fall of the Roman Empire)