I'd say that the regional accents aren't as strong and as "stereotypical" as they used to be - e.g. everyone living in wiltshire, talks with a "farmers" accent.
Because...I live in wiltshire myself :L - and I don't have a farmers accent - but now and then, words I say will come out - in a stereotypical accent.
I think it's not vanishing completely - but more people have become accustomed to "chav talk", so there's not much "regional accent" about anymore.







