The most recent reshuffle of Tesla Model S and Model X options and pricing (see report) also took away the leather seating option, leaving only synthetic seating.
Ultra White Premium Seats In Model S - 2016
It has been quite some time since vegans were lobbying for another premium seating option on Teslas, as originally you could not buy higher-trim versions of Model S without leather because some options were tied to leather seating in packages.
As a solution, Tesla introduced a synthetic leather option (Ultra White Seats) and now, another step seems to be the total abandonment of leather seating.
As synthetic leather is considered as more environmentally friendly, Tesla's move is in line with the promotion of offering more environmentally friendly, electric drive solutions.
Now it's only matter of time when we will see Model 3 design studio, which probably will re-confirm that there is no leather seating on any new Tesla, as CEO Elon Musk confirmed that there would at least be a "vegan option" for the 3.
We should note that the steering wheel is still leather-wrapped, but upon request Tesla will make sure that never moo'd either
Tesla Model X - interior options