Hey. All sorts of good comments!
There is no doubt that the public's needs/wants & local entertainment culture varies considerably around the continent, so I see everyone's observations & conclusions as valid.
I think that GuitarMikeB makes a great point. Dating habits have changed in a lot of the subcultures around North America, and in many cases, the idea of 'dating' for a while for before making a commitment (and, ya, 'hooking up'. lol) is less fashionable, so going out to see bands, do some dancing & chatting, etc is not as important to those millenials. For that crowd, a loud wild environment where you can check out the hotties & text them is more important than having interesting, creative music or being able to chat. (ironically, that was what disco was in the 70s!) However, in some social circles in some parts of the USA/Canada, the old-school dating rituals are still valued/expected, and it seems that country music is seen as a good genre for the 'slow, but sure' style of dating/socializing. One way or another, I'm not sure that there's much musicians can do about this trend except go with the flow.
IMHO, the other change with millenials is that entertainment is much more visually oriented now. My generation (baby boomers) looked to the radio for the main source of music, comedy, talk shows, interviews with up & coming artists, first listens to new albums, and so on. As far as TV went, it was important in terms of music as interviews with stars, variety show/talk show appearances, and the beloved "Don Kirshner's Rock Concert" were the rare opportunity to see the bands whose music we & our peers had fallen in love with. So, we loved the music first (for whatever reasons) THEN discovered what they artists were really like, and the act of choosing bands/artists was a cerebral thing to some degree. Now, the visual image of the musicians is inseparable from their music, yet (understandably) the big show/fantasy story provided in videos is not part of a live music act in the local bar, so millenials are not drawn to it as much. Furthermore, except for a portion of the population, music doesn't have the cerebral/discussion-raising appeal it used to have, so hanging out to see live music to stimulate the mind & conversations just isn't happening as much either. As far as dancing goes, for the over-40 population, it may be that the crowd that still makes the effort to go out to see live music was never into the dance scene when they were younger, so nothing has really changed. However, at weddings, company parties, etc you get a wider variety of people that includes some of the old dancing/disco crowd.
BTW, the post with the list of sure-fire dance tunes could be the start of a very good thread, especially ones that do get the younger crowd up on the dance floor. The challenge is that certain songs go in & out of style, depending on whether they are used in a movie, a TV show, a commercial, a re-issue/mash-up, and a variety of other random factors. So choosing a set list to get people dancing will always be an experimental science to some degree.

Ok...enough said...just my thoughts...
cheers,
Derek