I can only find one thing wrong with the sentence, maybe there should be a comma after languages, otherwise it's perfect IMO. I'm interested to know why you would say there are other mistakes?

You could re-write it to make it more formal I suppose:
As for languages, I am truly disgusted by the quality of written and spoken English among today's youth. I'm more worried about loss of standards in schools than I am about English turning in to slang.
But really there's nothing wrong with the first sentence in an informal environment.
This TED talk is very pertinent to the original topic (and it's awesome) a very strong case for saving dying languages:
http://www.ted.com/talks/wade_davis_on_ ... tures.html"The 20th century, a hundred years from now, is not going to be remembered for its wars or its technological innovations, but rather as the era in which we stood by and either actively endorsed or passively accepted the massive destruction of both biological and cultural diversity on the planet."