Hi,
Yes, the E-series is - and probably will remain - the worst of the digital cameras to support when it comes to the memory cards. And, it's all because of that one stinking pin!
I think all the other cameras will be easy to support memory-wise. Most of them use CF cards, and they'll be around forever. Then, there are adapters for other card types to CF that will also work.
The only issue might be that finding a small enough capacity new card for an old camera in the future might be a bit of a challenge. For example, that the old Kodaks have a 2 GB limit. But, there were so many CF cards under 2 GB made that they'll be all over for many decades to come.

Batteries may become an issue in the future, but I don't think so. Most of the older stuff, the D1 series and the Kodaks for example, use NiMH cylindrical cells. They're common and there are a lot of battery specialty places that carry such and many will even pop the sonic welds on the pack housing and re-cell the originals for a reasonable cost.
Only in the case should NiMH cells go away and only Li-Ion cells remain would there be an issue. You can't properly charge Li-Ion with a NiMH charger......
As I recall, the E-series had both NiCd and NiMH cell packs and I *think* all the chargers were smart enough to charge NiMH even if the original pack were NiCd. You know, since I stopped using an E-series years ago, and have sold off all of what I had, I'm starting to forget details.
Was the E-series NiMH aware, or only NiCd? As I sit here and think on it, I think there were two chargers, one NiCd and one NiMH and the NiMH was the same pinout as the D1 series charger. The NiCd was a coaxial plug, right?
Not that it matters. Even with all the gnashing of teeth over Cadmium in things nowadays, NiCd cells are not going to go away. It's the one and only battery technology that can handle rough service, as in police and fire radios, so they will continue to be available. They'll just cost more as time goes on.
As far as asserting that Hi-Speed pin on a PCMCIA card, it is easy. You pop the cover on a type-II card and use a 30 gauge silver teflon coated wire - what is universally known as a 'yellow wire' - from the Vcc (main input power) pin to the Hi-Speed pin. That puts a logic 'Hi' on the pin and makes the stupid camera happy.
Now, I no longer recall which pin numbers those were! I once had it documented somewhere, and I thought it was on here, but I can't find it now. Nor can I find it on DPR, where we chatted E-series a lot at one time. It may have been on Rob Galbraith's site, and that's gone now......
Somewhere in my mess of an 'electronics shop' I have 'feeds and speeds' for all sorts of memory chips and cards. Now, laying my hands on the binder that has that era's data in it might be a bit of a problem. I know I have it *all* still, but much of it is still packed up in boxes from a move 5 years ago!
later!
Stan