I have noticed that big cats are now starting to show up more and more. Back in the 1970s a Maincoon cat was just a slightly larger cat, now they seem twice as big. People are owning Servel cats (small wild cats) or they have cross bred them to make Savannah - a hybrid cat breed that looks like a mini Cheetah Big breeds like the Norwegian ForestCat, Chausie, Ragamuffin, and Ragdoll are now common.
I think people are breeding really big cats, because big is fun. "We have big dogs, but why not big cats", people think. Yet, I think there might need to be more restrictions. Someone could easily breed and distributed a house cat that was as big as a Labrador or Rottweiler without knowing what cats might be like or how big they could get . Can you imagine two cats that size getting out, turning feral, and breeding in the suburbs? And, once large size gets in the domestic cat gene-pool, it could spread fast.
I really think one of the genetic snafus that will happen in the next 30 years will be someone will breed a house cat that is too big. I bit too big and strong for its own good...a cat that will hurt people, but is then so wide spread it hard to control.