I grew up with a western mass accent, which is a sort of lighter version of bahston with less non-rhoticity. I can turn it off, but lately choose not to, also for social class reasons.
Distinctive communities get broken up now and disrupted by media.
Not so. Maybe this is true in many cases, but I personally know of at least one outlier: a relative who grew up in West Virginia, lost her accent to work in radio and news, and when older re-married to a man from Texas with a heavy accent and developed one herself.
It is also the case that many people slip back into accents as they age.