How long does Class A have?

Hi Guys/Gals
 I have a Sugden A21SE which is a Pure Class A single ended design, I absolutely love this musical amplifier with its strangely plentiful 30wpc, it runs hots as they do, I always enjoy watching the faces of my uninitiated friends when they touch it after I mention they get hot, lol.
But in this modern green era I wonder just how long do Class A amplifiers have before Greta Thunberg gets wind of this inefficient method of creating sound and pisses on the parade?

Thoughts?