Solarcity was bought by Tesla in a $2.6 billion all-stock transaction Nov 21, 2016.
Elon Musk has tweeted that he has the funding to take Tesla private for $420. I am quite sure thata majority of shareholders will accept the deal. The buyers probably includes the Saudi Arabian sovereign wealth fund.
Elon Musk will have some extra valuation on his Tesla stock, but will probably retain all of it.
Elon will not need to worry about quarterly earnings and can focus on the ten year goal.
Elon will be able to focus on making Tesla worth more than $650 billion by March 2028 in order to trigger the maximum performance bonus of $55.8 billion. Elon's shares would be worth about $145 billion if the $650 billion target was met. Elon would have $200 billion in Tesla valuation if Tesla reaches $650 billion.