there is a line of reasoning, rarely articulated, that EVs will
never reach the price points it would take to fully 100% replace ICE cars in the private/personal market.
li-ion batteries have done an excellent job walking down the learning/cost curve, but we can all see the way it bends and how much headroom is left in the chemistry. we'll likely hit $100/kwh in the next few years, but even just $80/kwh is likely 5+ years away after that. the model 3 will never start with a $2.
so if you're going to bottom out at around 3x the price it would take to fully replace the existing market... then you have to figure out a way to get 3x+ the value out of the asset you're delivering.
that means some combination of lasting 3x longer (~500k miles) and/or being in use 3x more (~600hrs/year). the former is viably unlocked by the EV engineering advantages, but w/r/t the latter, individual drivers have no intention of tripling their car usage. so it simply has to be turned into some kind of shared asset.
imho self driving makes this a nirvanna, so I'm glad they're pursuing it, but its not actually required. tesla could add a basic uber/lyft feature set to their existing app and then when the last 0.01% of self driving winds up taking years longer than elon said it would he can blame the regulators and just make it a regular human-driver ride sharing app.
remember the mission is the end of carbon emissions, so any plan for "lets just get good market share and margins in the luxury segment" is a plan to fail.