What happened to class H amp technology????

I had a class H Soundcraftsman A5002 250 watt amp from 1983 and had it extensively modded in 1992. I ran it hard and it never never got hot. Just a tad warm. It was driving an Ohm I which could handle a 1000 watts continuous. After the mod the midrange became tubelike. The bottom end had a lot of weight . There was a slight edgy upper midrange that was irratating. I finally sold it and went on to Bryston. However I'm still amazed how it was able to drive near clipping for hours and not even at a strain. So my question is class H a viable thing in the future or is it forever obsolete. It wasn't a bad amp compared to Bryston. Thanks for any responses especially engineers. Mike