I'm sure that TLG has a whole zoo of animals that they have not released yet. Timing on those element is probably tied to themes, sales, and forecasts, not to the products of other companies. Now, if there were a Harry Potter cow (or some other licensed theme with said bovine), we'd probably have seen their version come out a lot sooner.
I don't suppose BF would bring about any legal action, but if they did, would they have a hoof to stand on for copyright infringement? A LEGO-compatible cow, similar to the LEGO horse versus a LEGO cow. That's a whole different bucket of milk.
Meantime, let's enjoy the new moo makers, and not have a cow. Brickjournal has a review
on the 10193 set already, including these new beasts. I rather fancy the TLG versions.... yee-haw!