Yes, the language has changed. A generation or two ago, it would not have been seen as acceptable to say "If she was here", but now it is. The rules have relaxed, and only the most pedantic of grammarians would insist on "If she were here". Both forms are now accepted by the University of Cambridge examination markschemes.

I still tell students to use WERE in an exam - just in case! Not all exam boards are as enlightened at the Cambridge one. Some students sit their national exams - and the WERE form might be the one expected. Better safe than sorry! But I actually use the WAS form more often these days. I was brought up to say WERE, and would be corrected if I said WAS. However, as Su.Ki. says, times have changed. So I use them interchangeably - probably using WERE if I want to sound more formal. So my poor students get a complete mixture of WAS and WERE from me - I simply do not notice which I'm using! But they get a warning to use WERE in an exam - JUST IN CASE. I have some students who say their own teachers (in their own countries) insist on WERE - and this probably reflects their own national syllabus. But I imagine, in 20 years, all teachers and exam boards everywhere will accept WAS as perfectly correct. Perhaps there will be a slight distinction - WERE being used in formal situations/legal documents, and WAS being the usual form for everything else.