Two new traits I'd love to see would be tufted ears and kinky tails. The tufted ears are like those of a lynx - a bit larger ears, pointed & with tufts of fur at the tips. If you can make whiskers surely you can make tufts on the ears.
The other trait is a kinky tail - shorter than normal tail & with 2-3 kinks (sharp angled bends) in it. I've had two RL cats with this type of tail & it's SO cute!!