I was in the room at NAMM when the JVM and VM was being demo'd. Heck, I came back for the demo another two times over the weekend. I am also a Splawn dealer and have a decent amount of vintage Marshall Super Leads and a JCM800. I also have a Mojave Peacemaker and Splawn Quickrod in my studio.
I won't say the sky is falling for anyone just yet. I didn't play the JVM, just heard it being played by two different players with very different sounding guitars. I haven't put my Splawn or any of my vintage Marshalls up for sale yet.
I will say this...... all these companies and modders existed because Marshall was not actually building the Marshall that people wanted. Thank goodness that Mojave, Germino, Cameron, Splawn, Roccaforte, Cornford, Soldano, Bray, Bogner etc etc existed because for the last 20 years Marshall has been out of the game and out of touch with what players wanted. I think finally Marshall decided they wanted the entire Marshall inspired amp industry back in their pockets.
It's too early to say if they can do it. I have to play the amps and put them in my studio to see if they're worthy. But the fact that I'm even considering putting a production line Marshall in my studio with my boutique and vintage stuff is really saying something.
If I had a Marshall-esque based business right now, I wouldn't panic, but I would be very interested to see what these things sound and feel like.