Are future improvements in Amp/PreAmps slowing to a crawl?

Think most missed Nelsons real point-  {largely solved on a practical level} amplifiers have existed for decades that can run a loudspeaker reliably affordably and efficiently. 

I guess in terms of sound quality - gains will be marginal, but the means with which to deliver the results will keep developing - Class D and Class T amps being two such examples. My opinion is that with 'improved' technology logic will dictate amps will become:
1. Smaller and
2. More efficient
I think it is arguable that such amps may well have 'room correction' technology built in without the distortion affects of tone controls.
I thought that the likes of Tact/Lyngdorf was going to take over the world so to speak but oddly - as a company - they didn't - although digital amps appear to be the way to go for the majority of householders

One of the best designers of pre amplifiers and amplifiers Kara Chaffee designed a couple of tube preamplifiers. The Ultra Verve uses the 6SN7 tube. The key with this preamplifier is to let the tube do the talking. Keep everything so simple, class A single ended. Just get the most out of the tube. 

The point. Yes things have slowed and they should slow until there are real advancements in the way music is recreated and reproduced.

@parrotbee 
" I guess in terms of sound quality - gains will be marginal..."

There is a way to obtain massive improvements in sound quality. At some point there will be a realization that the missing link in analog amplifiers is how much attention is given to the velocity of the [music] signal passing through the amplifier. Unstable velocity creates an image that appears to have sonic "vibration". In much the same way as there have been great strides in discovering ways to limit mechanical vibrations, the same negative vibration effects can come from the electronic circuitry itself.

When this is addressed a radical drop in "interference " is removed from the image. As the electrical vibrations become less and less it begins to move in the direction of more and more "live". This is because "live" has no vibration interference. It is the loss of vibration interference that is recognized by the brain as a live event.