Disclaimer, this is not an official endorsement but rather a change of opinion.
I'll make this short since I've posted my thoughts about Hockey in Louisville on other Louisville topics in the Business of Sports forum. But I do think the NHL would be a better success in Louisville than the NBA. They of course would need the correct ownership and would need time, but I think the Kentucky Mustangs or whatever could become the Predators 2.0, or even the Hurricanes 2.0 (preferably w/o a 10-year playoff drought).
The biggest hurdle would likely be U of L sharing the KFC Yum Center. But everything else appears to be there.
-Population? Check
-Corporate support? Check
-No other major competition? Check
-Potential marketing to not only the rest of Kentucky, but also Indiana? Check.
Again, this is no endorsement. Just a change of opinion.
I don't think any of them are really checks.
Is the population really there? It is the same size as Hartford. That "just over a million" mark is tough to work with in Top 4 leagues. Buffalo is the only smaller NHL market, and they get by courtesy of unparalleled fan support (consistently the best league TV ratings among other things like ingrained hockey culture). Louisville certainly wouldn't have that.
Corporate support and no other major competition go hand-in-hand. University of Louisville basketball, and to a lesser extent football, are
major competition. Columbus Blue Jackets struggle financially because of the competition from Ohio State, and Columbus is a significantly larger market than Louisville. It is the reason why there are so few Top 4 leagues in places with big collegiate athletic programs. I doubt if there is enough corporate support, and possibly market interest, in Louisville they can survive off from the Cardinals leftovers.
For potential marketing, there are only one or two other heavily populated areas that are worthwhile. Lexington is around 500k and after that is nothing is worthwhile. Just about every small market NHL team has several large satellite cities as part of their draw. Louisville having one major one and a handful of significantly smaller ones just wouldn't be enough to sustain them.
All in all, it would be an absolute stretch. And that is in the best case scenario, where they do get a rich and dedicated owner and good dates at the KFC Yum! Center and the NHL deciding to expand and the NHL deciding to expand to Louisville before the at least 10 other preferable markets.