Scud-dog,
I am not convinced that flyrods are moving in the faster and faster
direction.
Some years ago, Fly Fisherman had an article about this subject,
and the conclusion at that time, was that rods had not become so much stiffer with time, but that their recovery rate and resonant frequency had turned slightly higher. Some manufacturers are getting attention by presenting somewhat extreme rods to the market, the flyfishing magazines are the servants that spread the messages. I donīt think the 0-weight issue was much more than a marketing ploy, at least if you are serious about catch & release.
The use of higher and higher modulus graphite, has turned out to be
like a blind alley, rods easely become too brittle, and from what Iīve heard, there are now more common with medium modulus graphite
usage,which in itself are benificial in making medium action rods, I suppose.
For a period, the pendulum can have a stroke in the direction of the fast-rod fashion,but with necessity, (very) fast-action rods are so demanding to use, that one has to practise a lot to be able to handle them,and as well , your degree of concentration has to be top-notch, which most of us doesnīt accomplish during a whole day of fishing.
So, donīt worry!

There will still be a lot of rods of the medium
action types out there, and more to come.
E.g. Winston and Sage makes rods that I consider medium action ones.Hardy Sirrus rods are said to be of the "right" brew.Loop
Yellow Line rods are definite medium actioned,if one can stand the color,thatīs it.Green River Jade,also comes to my mind.Loomis has some presentation oriented rods.
In my opinion, the medium action rod will survive,even prosper.
Why? As Buddha said to his followers,while sitting at the river bed,under a tree, and as a raft with some musicians approached
on the river.
Listen to the sound of the string, if too loose it wouldnīt
sing at all , if too strained it would brake.
Long live the golden mean, and the medium actioned flyrod.