So is the normal PHP way to create meta boxes going away? That's going to be a huge problem for me, having used that in dozens of client websites, for all kinds of extra custom fields. How am I going to fix all those sites breaking when this is released? This can't be true.

I'm absolutely no Js developer so rewriting it in Javascript will be a big problem. And I don't want to think about how clients are going to react to this, obviously they aren't eager to pay a lot of money to have me fix a problem that wasn't there before.

Really scared about the direction Wordpress is developing. It has always been the best option but the future looks dark.