Question:
How did you come up with the > 0.9 probability? Study of past S&P 500 inclusion event and the companies ER (+ve EPS by summing last 4 quarter EPS)?
Yes, the S&P 500 inclusion rules are unambiguously defined by S&P committee, the most important of which is that the sum of the GAAP income of last 4 quarters must be positive, and the last quarter must show profit.
If Tesla's Q1'19 is profitable, then Tesla will very likely meet all the criteria and will be included in the S&P 500.