there are still enough advantages to the single handed backhand – the trouble is that kids learn a double hander when young as it seems stronger, and then never change as they don’t want the risk, or to take the time to change.
The single hander is a stronger shot – the double gets its advantage from wrist control but you can’t coil up your whole back and unleash through the ball in the same way.
And I don’t think the double is easier to learn, it’s pretty easy to learn a top spin backhand – you just turn your back to the ball and then hit through it – simples.
When there are no singles left I probably will watch tennis a lot less.