sadly, yeah it seems Mashima has lost any enthusiasm for this story/ these characters. 100YQ has just been phoning in the most basic story possible. (by that, I mean I’m sure character design and storyboarding is still a lot of work, just he’s not interested in adding to the lore of the universe much further, or coming up with demanding intricate storylines with decent twists).
I’d still like to see something like a “Fairy Tail - S Class” follow-on, but it would depend on if Ueda was willing to take full control. I think he’d probably be coming up with better stuff at this point. Still have nil interest in a next generations series, I don’t like the dynamic of Boruto and I don’t see how this could work any better tbh.
I think it's different, FT fans are much more willing to read a new FT story than Naruto fans.
The plot of the 2 stories are different, FT gives place to explore and tell many stories (usually focused on Natsu and Lucy but also on the other members of FT), while Naruto is more linear, since it has (had) a goal.
We see this in the large number of stories told in spin offs or light novels that FT has: Ice Trail, Blue Mistral, Gaiden, Happy's Heroic, Trouble Twins, Wonderland, Zero, etc.
As for a "Next generations" of Ft, it would work much better than boruto:
1) The couples, it is clear that the Nalu is the most popular ship in the series, unlike the Naruhina that was not really liked by many. And not only the Nalu, even though FT is not a romcom, the series has better couples than the Big 3
With this, I am sure that many of us would be happy to see a series with the children of Nalu and the other couples.
2) The "family" dynamic with Naruto and boruto was a disaster at the beginning of the series, and that was because Naruto never touched on the "family" theme within the main series, while for FT the family theme would not be something new
3) Boruto has a lighter tone and with more comedy than Naruto, with this, it is clear that boruto was not going to generate the same level of quality and narrative that Naruto had, while an NG for FT, can give the characters that "push" of maturity and responsibility they need to grow.