The only way I can see Tesla going to cf in the near future for the model s (remember it has to cost ~50k and be profitable) is that there is a significant reduction in the price of batteries. SO that the use of CF will help increase range (due to weight loss) without impacting either the price of the model s or Tesla's margins on the S.
This doesn't make sense. Say it costs $10,000 to switch from aluminium to CF, but it reduces the needed battery capacity for the 150 mile range car by 5 kWh. Then it would be economical to use CF if the cost of 5 kWh of battery was more than $10,000.
If the battery price goes down, then it would make less sense to use CF, not more. You'd need either the battery price go up (heaven forbid!) or the CF price to go down.
(Don't take these numbers as correct, I just made them up for the example.)