I am personally affected by the BMS changes (both lower range and lower Supercharging rate), and even *I* am not sure if Tesla has a legal obligation to replace the pack (though I am no legal expert). They issued a software update to correct the safety issue as soon as it was discovered, and do not have anything in the warranty (for packs of that vintage) saying that degredation cannot exceed some specific amount. So from a safety perspective I feel like they're covered.
However, the bigger concern to me as a big TSLA stockholder is in the negative impact to goodwill on the customers---many of whom (like myself) are very early adopters of Tesla products and felt not only rolled over the coals, but were never given an up-front explanation from Tesla. Many of us have a sour taste in our mouths as a result of how this was handled, and it does leave the impression that if you don't drive the latest and greatest car, Tesla doesn't care about you all that much. Not saying that's actually the case, but many affected feel that way--as much as I want to cheer Tesla for everything.
I hope they at least make some sort of gesture of goodwill toward those affected. We all want Tesla customers to be happy, right?
I feel bad for people like you in all this, because now Tesla basically can't do anything for you (at least until the lawsuit is done), as it would be used against them as an admission of wrongdoing. I fully agree that this should have been a goodwill issue. I hope that once this mess has blown over, that they do some sort of goodwill option for you, like offering at-cost upgrades to new 100kWh LR packs, or some cash / store credit or something like that.
Also, the reason for the NHTSA filing is simple: they're getting the NHTSA to do discovery for them. Normally in court you have to fight for the right to force discovery on the defendant. Here the NHTSA will do it for them.