Nice thoughts, and some good suggestions. Many of us have offered ideas for books to add to the heap. IME they're not interested.
The business of publishing guidebooks is circling the drain, has been for a while, and continues to race towards oblivion. Anyone paying attention to the travel guidebook scene can see this pretty easily: most existing travel guide publishers have either gone out of business, or have downsized and morphed their once-great books into lightweight, eye-candy fluff that's little more than photos and a bit of added text that reads like it came from social media posts. As someone who has a whole room full of guidebooks I've purchased over the years who laments this trend, I can only think of two publishers that have resisted this dumbing-down of the traditional guidebook (Rick is one; the other is Bradt, which continues to publish wonderful, content-dense guidebooks, even for some pretty obscure or "small potential market" destinations - all the others, even the mighty and once admirable Lonely Planet series - have gone down the flush tube).
Market/demographic changes now come with a collapsing interest in books (ask any traveler without gray hair that you meet which travel books they've bought for their trip). By and large, most people today can't be bothered to read books (never mind spending $20-$30 on one). OTOH there are countless bloggers, youtubers, ticktockers and others working hard for online eyeballs, some of whom may actually be worth a glance (but most of whom are not). Add to that the infection and proliferation of AI-generated "junkbooks" - go look at Amazon and search for (anyplace in the world + guidebook), and you'll find "guidebooks" scraped from the internet by people who have never ventured beyond their mother's basement. This theft and brain-dead plagiarism will be the final nail in guidebook publishers' coffins.
It's nice that RSE has continued to soldier on updating their books (which ain't cheap), continuing to publish longstanding titles and even adding a new one occasionally. The books continue because (just like this forum) they help support the company's tour business; as long as the tours are highly profitable, the books can probably be justified - though from a "strictly business" perspective they probably will be a prime target when the next pandemic/recession/worldwide economic upheaval and inevitable cost-cutting comes. I'm sure the RSE guidebook division is a sentimental favorite for the Founder (and that counts a lot in any business). But in case you haven't noticed, the Rick Steves empire has been evolving for a long time: the pace of new content created for TV has been declining for years - it's now mostly thematic "specials", rather than a full season of new-destination shows (the specials are great but new shows on a dozen new locations would be greater). The Edmonds Travel Center which used to be open (IIRC) 7 days a week has been reduced to Saturdays only (since re-opening post-COVID). Rick has been at this a long time, it seems to me he has been quietly "retiring" in many ways (though he's obviously still a workaholic). He's a good man (I've met him a few times and wish him well) and he deserves to allow himself to slow down a bit and savor things; time, age, life changes and their consequences impact us all.
No doubt the businesses are set up to continue, but personally I am not expecting a lot of new guidebooks going forward. Over the years I've quietly suggested a bunch of potential destination guidebooks (I've also tried to share thoughts on how the business might continue to evolve and take advantage of new opportunities) but there seems to be zero interest in any of that (at least from "outsiders" - I've never received any response at all, even when applying for entry-level jobs). So it is what it is, and who knows what it'll be in the years ahead. I'd suggest we should all enjoy the books while we can.