Let's just repeat Tesla's press release, dated August 23, 2016, and published on the Tesla website:-
"Tesla customers who have ordered a P90D Ludicrous, but not taken delivery, can upgrade to the 100 kWh pack for $10,000. Existing P90D Ludicrous owners can also upgrade to a 100 kWh pack, but for $20,000, as their used 90 kWh pack will have to be recycled. "
Tesla may be regretting having said this, but they can't take their words back.
Now, I'm not a lawyer, but I can see that they might drop the $20,000 upgrade - since the existing P90DL owners had taken delivery of their cars, so the upgrade was not part of the "contract of sale", and so they weren't entitled to this: it was a nice gesture, but I can see that Tesla might decide to do away with it.
The $10,000 offer - for customers who hadn't taken delivery of their cars - is a completely different matter. For many of us, the upgrade offer was
effectively part of our contract of sale - to the extent that we considered cancelling our orders, but were persuaded not to do so under the promise (repeatedly made, in my case) that the upgrade would take place, and within a definite time frame ("early in the new year"). I really can't see how Tesla can get out of this!
I can see that Tesla might decide it's not economically - or technically - feasible to do a battery swap (although some P85D owners had this done).They would then have to replace our cars with new P100Ds - simple as that.
Again, I'm not a lawyer - I prefer to see things in black-and-white, not shades of grey - maybe others have thoughts on this?