ABBA are certainly trendsetters - their tribute act, Bjorn Again, were the first tribute band to play shows with the same level of production values (and ticket prices) you'd expect from a "proper" band (before them, tribute bands were playing in local bars) - today just about every major artist has tribute bands, and they're no longer considered a joke, and Bjorn Again actually licence their name to franchises in other countries (!)
Mamma Mia! was possibly the first artist-specific jukebox musical, and remains the most successful, today there's dozens of them, from We Will Rock You to Jersey Boys and Beautiful. It's the way legacy pop music finds it's audience.
ABBA Voyage may not be the first hologram show, but it's the biggest to date, and the first in a bespoke arena. It needs to make billions to break even, and all signs are it will. Bespoke ABBArenas are being planned in other territories.
So yes, this is the future of popular music.
Expect to see Queen, The Beatles, and every other legacy act you can think of coming to a custom-built holo-arena near you. There's a reason music isn't what it used to be - and that reason is that it's exactly the same as it ever was. People don't want the new, they just want the old, re-sold to them over and over again.