NHL Europe doesn't make sense as an expansion to the league, or as an AHL style development league.
As pointed out, time zones are a killer here. A 7pm east coast start is 1am in Berlin. As a development league, what's the point? It's not NHL level, so it'd just be elbowing in on the existing IIHF ecosystem, and NHL teams can loan players to Europe already.
The Irish national team can't compete in IIHF events, and hasn't in more than a decade, because they don't have a suitable rink anywhere in the country. 5 million people.
Florida, the US's third most populated state, has 17 local rinks. Something like 1 rink per 1.35 million Floridians.
There's a financial issue with the high costs of hockey that has to really get cracked before the game (league revenue) can significantly grow.