Back to the OP, sure, price probably has something to do with the drop in pop-up sales. Though, I'm not sure it is anywhere near the main reason. Look at the A-frames, they are flying off dealer lots (compared to many other RV categories anyway), are a type of pop-up, and are priced up there with the hybrids and cheaper TTs. Heck, while many pop-ups certainly can be overpriced and overweight, pretty much every pop-up manufacturer puts out one 8' and one 10' model (and often a 12' model) in their economy lines that are reasonable on price and weight (Jayco 8SD, 10SD, 12UD; Flagstaff 175LTD and 206LTD; and Rockwood 1640 and 1940 for instance).
I think a bigger factor is demographics. 20 or 30 years ago, you would see many families out there camping in pop-ups. For a family a pop-up has definite advantages over a TT. A pop-up has dedicated sleeping space for a family of four without having to convert a sofa or dinette to a bed. For a family with more than 2 kids you will need to convert living space to sleeping space, but a TT with sleeping space (even converted sleeping space) for more than 4 will be getting quite large, heavy, and expensive. Today, most RVers are older with grown kids. That demographic doesn't need as much dedicated sleeping space so the more restricted sleeping areas of a TT (or A-frame) aren't the disadvantage they are for a family so the TT becomes more popular. If you don't need the big advantage of a pop-up (more sleeping area in a smaller space), why deal with the extra set up of a pop-up (especially at a demographic where arthritis and other aches and pains start to show up).
Related to the above, living situations may make TTs more popular. Someone already mentioned housing costs keeping many younger families out of buying a camper due to tighter finances (and we all know that real income has been declining over the past 30 years). Also, related to more older folks and fewer families in campers, I suspect that living situations due to an aging RVing population may negate one of the big advantages of pop-ups. One of the big advantages of a pop-up is that you can store it in your garage. With a larger TT, many communities don't allow you to park them on your property so you have the extra cost of storage. Well, my parents just bought a 55 and over condo and are about to move out of the house where I grew up, and an aunt and uncle did the same thing (in a bungalow) a few years ago, and they aren't alone. Many older people are moving out of the houses (with garages) where they raised their kids into over 55 bungalows (with tighter spaces and streets where pulling a trailer would be tough), over 55 condos and regular condos. Living in a condo or apartment, you may not be able to store your pop-up on the property, so with either a TT or pop-up you may need to rent storage space, thus negating one of the biggest advantages of a PUP.
Now, over the past couple years, I seem to see more and more young families rediscovering camping and I see many out there tent camping. I'm hoping that as many of them decide to move up to something more comfortable we will see an uptick in the pup-up market. Even if we don't, I think the declining sales is far more complicated than just the price of the units.
Tow Vehicles: 2016 Kia Sorento LX V6 (sold)
Other vehicles: 2019 Hyundai Sonata Sport, 2021 Hyundai Ioniq EV (a hatchback so great for tent camping, but needs an electric hook up to charge the car)
Camper: 2003 Starcraft 2406 (sold)
Several tents
