And ultimately, that's the real issue, isn't it? The old D series drivers die (and the K series, too), and there are no proper recone kits, and no new drivers that sound the same. None that I know of, anyway. There's no end of great gear out there, but none that gets the same sound produced by vintage JBLs. Again, none that I know of. I suppose that, if one had enough money to spend, one could contract with Eminence to duplicate the design. That should work, if the same materials are available. But I don't have anywhere near that kind of money.
Oh, well. Waddaya gonna do?