Nice summary. But I think we need to consider the possibility that the committee will simply decide to take some alternate action, possibly based on TSLA inclusion being too disruptive at this time. An abrupt rise followed by a similar crash isn't really a good thing for anybody, except a few day traders who get lucky.
Another possibility that doesn't contract the float is if current institutional investors have already accumulated shares and agreed on private sales to S&P tracking funds. After all, S&P 500 inclusion has been an obvious eventuality for a long time, so it's reasonable to guess that plans have been put in place to avoid chaos. These people aren't stupid, and it sure ain't their first rodeo. This is pretty much what I expect is the case.
So what happens if the powers that be don't play along with the "IT'S GOING PARABOLIC!!!!" crowd? What's the reasonable level for TSLA? Does it hang around 1200 into earnings, or continue up to something much higher (my Jan '21 1800 calls would like that!)? Does it fall back after earnings, or sit around waiting for battery day? Or continue up? All a mystery. But all things considered, I wouldn't count on the S&P 500 event to do anything much for the stock price beyond what's already happened.
Be careful out there.