It seems almost a given that Verstappen will leave Red Bull after 2020. Ferrari could tank again next year but I don't know it that would be enough for him to stay at RB. He will be sought after, for sure.
Verstappen had better take notes though, being disruptive and burning bridges (Max, why piss off Ferrari?) doesn't pay off long term.
As Alonso continues to look for a way back, his history stands in his way:
There have been rumors that Liberty Media looked into the possibility of Fernando Alonso joining Red Bull Racing for the 2020 season.
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We immediately said we have no need for Alonso,” Marko told Auto Bild. “It won’t work because our engine partner Honda won’t have it either. The name Alonso makes the hair on their necks bristle.”
We have to give Max a car in 2020 with which he can become world champion. Otherwise, he will be gone,” said the Austrian. “Right now things are really going on behind the scenes. It will be decisive weeks.”
https://www.gpblog.com/en/news/5192...e-makes-the-hair-on-their-necks-bristle-.html