The drums are still available. Now, I know that Brembo quit making the aluminum drum, but the steel one is available from numerous aftermarket suppliers, or at least it was last October when I checked.

We had the drums NLA discussion a few months back but I'm too lazy to dredge it up again.

Bottom line is that you can get drums that work (maybe not optimal, they weigh 11 lbs versus 6 lbs for the ally), and a change is against the core IT philosophy.