I wonder how long it will be before the 2WD model S is gone. It would simplify production if all X and all S are AWD. I believe they are made on the same line, and the extra mass production of the AWD will lower costs even more.I doubt if the cost is all that much more for Tesla, and AWD makes lots of sense to many buyers. Few would turn it down if the costs were similar to the 2WD model. I have heard that AWD Teslas are the bulk of demand now ,and no doubt that will increase with the 70 kWh model availability. Who knows how much of that is backlog demand and how much sustainable demand.
Furthermore it would be a mark of separation for Gen 3 to be 2WD and the more expensive Tesla cars to be AWD. I know Subaru has gained market share over the last few years, probably based on it's AWD abilities.