He'll be back
He'll go and help Indycar become 25% more popular overnight next year and once he has won both the Indy 500 and Indycar champion title he will be back to race a competitive McLaren in F1.
He will win the WEC series world title (LeMans cars) for Toyota this year too.
Winning Monaco/Le Mans/Indy 500 is the "Triple Crown of Motorsport" and has only been done once.
Alonso wants to go one better and win all three Plus become champion of all 3 series as well.
Exciting times for him and us!