A lot of large corps (in my neck of the woods) are trying to get away from those and have started to move towards RESTful/JSON implementations.
Definitely. I also see a progression from Web Services to JSON services to RESTful JSON services. I learned XSLT before it was even an official spec and I think I can say I am truly an expert in it, but as a general programming skill it does not open doors. In my technical writer role, I do use XSLT quite a lot, but not for anything else.