i think he just gets it wrong ...
The kemper is not going to hurt amp sales . if anything it drums up an interest in tube amps for people who dont have access to them but they hear a profile they like , now they want the real beast .
I think there will allways be a demand for tube amps , like theres a demand for classic cars. .you can get a replica , but the original holds value and ussually goes up as it becomes more rare, example marshall plexi hella expensive... mesa mark iic + insane expensive