Personal opinion as someone who isn't in their twenties nor really grew up with Pokemon (I only started playing the series when I was 12 in high school, which was about the time BW2 came out and the best you could emulate on a phone was the GBA w/ GPSPhone), but Pokemon is usually at its strongest if it doesnt try to tie itself down to existing concepts.
See -> Let's Go. I actually really liked Let's Go. It was a fresh take and really tried out a number of cool new ideas from Pokemon GO that made it possible for me, aka someone with only tangential tedency to play Pokemon GO (limited data plan and a desire to not go outside much rather restricts ones enjoyment of it) to enjoy what Pokemon GO could add to the table at least when it comes to Pokemon catching. Plus it was nice to see the walking gimmick brought back.
Or here's one for a closer medium: The anime. I don't like the main anime, it's... too stuck in upholding the status quo (see -> Ash somehow being around for 20 odd years and a. still being 10 and b. still somehow being incapable of a proper Pokemon fight at the beginning of a new region). On the other hand, when they tried a more "realistic" (so Pokemon being animals again instead of mostly just repeating their own name) approach to the franchise and not make use of a character that for merchandise purposes has to receive no character development at all (Mario also peeks around the corner), the results tend to be so much more impressive. See Pokemon Generations and Origins for what I mean by this. Origins especially I'm disappointed in that it didn't receive a full season anime (imagine 12 episodes, 1 episode introducing Red, 8 episodes showing his journey to get the badges, 1 episode for Elite Four, 1 episode for Champion and a buildup to Mewtwo and one episode for Mewtwo), there's a lot of potential there for a more appealing Pokemon universe.
I'm not sure if this movie will bring something similar to Origins and Generations to the table in terms of characterization of both the Pokemon and the human characters, but it seems to be putting it's eggs in the same basket which at least from my perspective has a lot more potential to be good than the normal Pokemon status quo.
Oh and if it flops, we can always stick Deadpool footage over detective Pikachu.
It's bold to go for a sequel right away, I'll say that much, but... who knows? It could go very right, it could go very wrong. Maybe it's needed because of the plot of Detective Pikachu not fitting into one movie (I don't know, never played the 3DS title), but... I suppose we'll have to wait and see.