Like Quiltingshortimer I have only attended a couple of big national shows. MQX New England and the AQS show that was in Syracuse for two years. Due to poor attendance in both classes and the gate, the Syracuse show was discontinued. So shows, especially major ones will fold if they don't get enough attendees to make a profit. I have never attended Houston or Paducah. I would love to go to either one or both some day.
My best quilt show buddy and I are super frugal. We pack lunches/snacks to bring with us as well as our own bottled water, we wear backpacks to haul our stuff around. We rarely eat at the venue. I save for splurge purchases like hand dyed fabric or wool applique kits. The thread vendors (Superior, Filtec and Wonderfil) almost always have a deal so I also pick up thread at these shows.
Shows are incredibly expensive, both for the attendee and the promoter. Venues charge insane amounts and the vendors also have to pay crazy expensive fees for a space. Many of the big names also sponsor the prizes (like the major machine manufacturers, and Superior threads) so if they don't do well vending the price funds will dry up as well.
I always enjoy shows but I don't feel the need to attend every single year. I think many feel the same way. I suspect there won't be as many shows if the trend continues.