After completing our first long range road trip this summer (about 2500 miles round trip) and visiting many SCs along the route, from a road trip perspective, we would like to have a larger battery pack for our next Model S (than our P85), because we had to slow down several times to stretch our charge enough to make it to the next SC. A 100D is likely to have about 20% more range than a P85, with about the same performance. Will that be enough?
We don't need the larger battery pack for daily driving, I've never had to recharge the car during the day for driving around town. We've only needed the longer range when taking road trips - on routes with superchargers.
Assuming superchargers are spaced up to 150 miles apart, and driving at typical highway speeds and road conditions requires about 200 miles of rated range capacity to make a 150 mile trip to the next SC, and that we want to keep the car between 10% and 80% charge levels, then the rated capacity of the battery pack would need to be around 285 miles - which is the current 90D.
Increasing the capacity above that provides an extra cushion for higher speeds or poorer driving conditions (like higher headwinds or elevation changes).
If a 100D has a rated range of around 320 miles - that may be good enough to effectively use the supercharger network. And going to 125 or 150 may not provide much real value to owners, and justify the 25 to 50% price increase to get extra capacity, that would not really be needed.
I had "range anxiety" when I first got our P85 in early 2013 (and there weren't any superchargers). I no longer worry about daily driving.
We had "range anxiety" for our first long range road trip this summer, and the battery capacity of the P85 did require monitoring of battery usage and more careful planning of how much charge we needed at each supercharger (the on board trip planner was always much too optimistic).
Whether it's a 100 or a 120 or a 125, Tesla will need to continue increasing the battery pack capacity until the capacity is large enough to allow drivers to make long road trips, without having to monitor energy consumption and recharging and allow the drivers to drive as they would with an ICE, between the superchargers.