Interesting, this is the first I hear of this, do you have a source for this information? AFAIK the basic DL-103 output voltage and coil resistance specs have stayed the same through it's life, but to keep same output and same coils but change the magnet, wouldn't you have to change everything? Unless they use the exact same magnetic structure but with some sort of alloy to match the magnetic properties of AlNiCo close enough... or changed the wiring of the coils to thinner type to keep same impedance but lower inductance to keep same output with the newer, stronger magnets. Or something. I'm not sure how that stuff works and how easy/difficult that would be to do. Btw. I'm certainly not the type of person who thinks a magnet is a magnet, and while guitarists and hifinuts alike can be sometimes a bit "conservative" and/or batshit crazy about their beliefs, there's a lot of people (myself included) who just haven't quite experienced the same tone from a guitar pickup using magnets other than alnico, not that I've spent that much effort into the subject though.
I believe the biggest reason for the continued affordability of the DL-103 is the ability to keep chugging them out like they've been doing for decades, and especially since 2002 I doubt their production rate is that high, so it would seem on the surface of it than any major change would be more cost than profit. I'm not trying to dispute what you say, just would love to learn more of this and my google searches on the subject turned up pretty dry, other than some speculation on this very forum And even if they kept the same magnetic structure, wouldn't be surprised if they changed something else with the ownership change - or the magnets if it's a change they could get away with without redesign. Btw. if I'm not mistaken (which i very well might be...) AlNiCo magnets are not entirely stable overtime, so it seems likely a cartridge manufactured 30 years ago would sound different than a new one even if they were identical.