My local one has had gradually dwindling stock over the past year or so, and the last few times I went in, there were no bunnies or guineas in the sale area. Only a couple of rabbits in the adoption bit. The hamsters and rats were still there.
Maybe they are doing more ordering in rather than live stock constantly being there, I mean the critters grow very fast and I can't believe they would manage to shift them all at the amounts they had.
I think live animals in all areas of sales are becoming a massive money loss. Things like farms and zoos have ever more regulations and upkeep costs, and pets live for much longer as people take care of them better, so you arent getting the high turn over. I remember when peoples rabbits and guinea pigs never really lived past 3 years. And hamsters!
I know rats have a very short life span, but the others have reasonable ones I believe.
And I think more people are turned off the idea of pets nowadays, rented places often wont allow pets, they cost time and money which people have less of.
It may be live ones switch to breeders like with dogs and cats, but I think that comes with its own problems to be honest.