Do any of Elon's timeline tweets count as a promise?
In the vernacular sense, sure.
Legally? Likely not. Nothing he said is shown to you during the purchase process or as part of any contracts between you and Tesla.
It might color the jurys opinion in your favor if you get away with mentioning what he said in court of course, but they don't represent any sort of contract between you and him.
If his tweets (and Tesla's own webpages) don't count as a promise, why do they continued to be treated as such?
What you are promised in the list of "Here is literally what you are buying when you check this box on this page to buy it" is different than "What someone posted to the general public on twitter"
What exactly is a timeline promise?
To my knowledge Tesla, in anything legally binding, has never promised any specific timeline for L4+ driving.
THAT said.... they DID actually make specific timeline promises they broke... ironically in the POST 3/19 pages.
They promised both stoplight control AND driving on city streets as part of FSD by the end of 2019.
They failed to deliver either.
Then the page promised both by the end of 2020 and they failed to deliver the second one.
But they also made the disclaimer broader in the post 3/19 era- adding the additional "out" of achieving reliability far in excess of human drivers as demonstrated by billions of miles of experience before they enable any feature.
If you want another broken promise, a more active one, check out the CURRENT full description of Summon on the purchase page where it claims "Activated by the Tesla App, your parked car will come find you anywhere in a parking lot"
When of course that's only true for very small values of "parking lot" given how limited the range on it is.
There’s no reason for them to stop working with on it till all cars sold pre 2019 are off the road.
I mean- they'd have to continue to show actual effort and progress too, not just SAY they're working on it but not actually improve or update anything for years.