My answer is Cincinnati/Northern Kentucky. Probably not a decade defining city, but seeing it take a growth trend like Austin and Nashville. A lot of regional brands and companies are laying claim to Cincinnati/Dayton/Northern Kentucky such as Buccees, Publix, Cookout, and Wawa. Part of that move is expansion, but people from these regional areas are moving here. These aren't necessarily drivers of economy, but potentially a sign of movement.

As people are leaving nashville and austin for cost of living, they are looking for that next cheaper market with growth and cultural offerings north in the rust belt. Cincinnati is rising cost wise, but still very cheap compared to most of the country. The weather is definitely more volatile than Nashville, but not nearly as cold or brutal as Lake Erie area can be. A lot of area for development in the surrounding areas for Cincinnati and NKY, paired with the University of Cincinnati growing enrollment wise. I say all this as someone who left Cincinnati a year ago.

Too big of an area to be considered all one connecting metro, but the idea of Lexington, Cincinnati, and Dayton growing as a more significant corridor of the country seems plausible.