It is interesting seeing it evolve in a place like Charlotte, where I live and grew up, versus other parts of the state.
Most of the folks who grew up in Charlotte prior to the 1970s have fairly thick southern accents. Most, but not all, who grew up in Charlotte in the 1970s and 1980s, and whose parents are both from the south, have southern accents but generally much less pronounced than that of their parents/those who grew up in Charlotte prior to the 1970s. Those who grew up in Charlotte that timeframe who have at least one parent from somewhere other than the south have even less of a southern accent, if they even have one at all. Just about anyone born after the 1990s who grew up in Charlotte has no real detectable southern accent at all.
I see that evolution with my brother-in-law and his family. He is from a long line of Charlotte natives. His parents, who grew up in the 1940s-1960s have very thick southern accents. My brother-in-law, who grew up in Charlotte in the 1970s-1990s, has a noticeable southern accent, but nowhere near as pronounced as his parents’ accent. His and my sister’s teenage kids have no detectable accent. None of my kids’ friends have any detectable accent.
It’s also interesting that I often notice that Charlotte natives about 5 years older than me, and whose parents are from the south, have slightly more pronounced southern accents than Charlotte natives who are may age, including their siblings.
Meanwhile, I meet younger generations from some towns and more rural communities in NC and their accents haven’t changed much from older generations, and remain fairly thick.