There will always be "kids" at nma gigs (people under 30 by that I mean!) and it's constantly surprised me how many there are for an old farts band!.the word spreads
This is probably more noticeable, more obvious in Germany or England, where NMA has the bulk of its fan base and plays to 1,000 to 4,000 people in large venues. In France, NMA plays in small venues (capacity: less than 1,000, often 500 ). But even if you don't see many people under 30 at their concerts in France, at least you have the chance to see the band in small, intimate venues!
the Cure's latter career sucess has prob helped the genre too..
I imagine it mainly helped the already somewhat known, "mainstream" 80s bands? But it would seem so, that for about ten years there has been a "revival" of 80s culture (music, movies) through series like "Stranger things" which I mentioned earlier and which perhaps also benefits lesser-known bands like NMA...an 80s "nostalgia"/revival which brings some young fans to the bands.
"guitar rock" in general has been in demise for over 20 years now as other more tiktok friendly genres and artists become all consuming..can you remember the last big rock/indie act that broke through?.. genuinely I think it was mid noughties and maybe the kaiser Chiefs or the Libertines...around the same time as the social media explosion which has changed everything.
Certain genres will become "historical genres" not long from now and unfortunately consigned to museums like rockabilly..punk and jazz already have..
That's exactly what I meant in my initial message. When I go to NMA concerts in France, and others Rock concerts in my small provincial town, or even when I go to see relatively young, fresh american Blues/Rock artists in Paris, the audience at these concerts is essentially made up of people with graying or white hair (or bald!) in their forties? fifties and beyons. It's simply an observation about Rock and its audience in the 21st century. I remember that in 1994/1995, I was 16 years old, in high school, and all my teenage friends listened to 90s Rock (and also artists from the 60s/70s: Pink Floyd, Hendrix, Led Zeppelin, Zappa...) and most of them were guitar players in small local bands...there was a real craze, a real popularity of Rock (mainstream or not) among young people at that time...but it was perhaps the penultimate time, as you write with the few bands you mention that were "big" in the mid-2000s. The big positive here is that while Rock has been reaching a limited, "niche audience" for about 20 years, it allows us to see our favorite artists in small venues, without being lost in the crowd or needing giant screens to enjoy the concerts!
look at the arenas and stadiums that rock and indie bands are selling out!
Does NMA play in arenas and stadiums in England and Germany? Well, last year they played at Wembley, okay, but it was as the opening act for Billy Idol...and they played in front of 50,000 people in Berlin...but in 1987, as the opening act for David Bowie.
on the metal scene in particular, I saw 90's doom rockers Paradise Lost last year and there was a fanbase from teenagers to guys in their 60's / 70's and a great time was had by all! 
I agree, Metal appeals to young people, both newer and older bands. I'd even go so far as to say that Metal "speaks" to youth more than Rock. When I see the big concert veeues in Paris or the stadiums packed for Metal concerts, there's clearly a much larger (and younger) audience. Just look at the enormous success of the Hellfest festival in France (where NMA played four years ago... on the festival's small stage); Metal has a large, loyal, and young following.
Getting back to Guillaume's point, T+C came out in 1989. 1989 is now 37 years ago. Back in that wonderful year would anyone be asking if the tunes from 37 years ago were still relevant and why weren't people listening to them? That would be 1952! The top acts there were the likes of Vera Lynn, Bing Crosby and Doris Day!
Indeed, in 1989, when I was 10 or 11 years old, I didn't listen to these artists! Not even Elvis Presley. However, in 1995, the year I first listened to NMA through the cds of THUNDER, CAIN and RADIO SESSIONS, I also discovered (thanks to CDs given to me by my older brother) "old" artists from the 70s like Thin Lizzy, Tony Joe White, Neil Young...artists who had released some of their most significant albums before I was even born.
