I'm more at the coal face of this at the moment, as a book shop owner, and here's a few observations
Who are the customers? Whilst there is a sense that it's all become tik-tok, that's not the case - it's one market that's doing very well, but it's only one segment of the shop. They are mostly female, mostly young, but across a vast range of interests, and demographs.
Other than that, we have such a range of customers from men who like their non fiction (and, yes, they like their space ship books, too - but that doesn't represent the bulk of sci fi sales and my sci fi readers are evenly split - that's not so much with fantasy at the moment, where the traditional stuff is mostly selling to blokes, as a high percentage of the female market seek out the booktok romantasy style)
grandparents who like their grandkids to be reading
Families
young people who read more than most people actually realise
Fiction is still the best selling section (although at christmas this skews more towards non fiction. making them closer to even), with crime being the biggest sub genre (most romance is online these days, but it still dwarves all other fiction areas)
For us, Irish publishing is critical - and it is a market that does celebrate great debuts, and has good infrastructure in terms of review places, festivals, and word of mouth vehicles.
But the mid list is what's suffering, particularly in fiction. The supermarket model is terrible for pretty much all sectors of retail - they killed the magazine market, have damaged books wholely, and don't talk to me about trying to get a shin bone for the wee dog... - and, really, we should do everything we can to actively not shop there. For choice, jobs, range, the planet and sustainability.