But that was before he obviously enjoyed the experience of skipping Monaco and being competitive in the fabled Indy 500.
So when asked if he might switch full-time to the Indycar series for 2018, he said on Sunday: "Why not? I'm very open to anything.
"I would be lying if I said I know what will happen next year."
Marc Surer, a former F1 driver and now commentator for German television Sky, said he thinks a full Indy switch is actually a probably outcome for Alonso.
"Basically, there are only three ways for Fernando," he said.
"He either stays at McLaren-Honda, he returns to Renault, or he does a full season in Indycar.
"On the normal (Indy) tracks he would beat his opponents, and he has shown at Indianapolis that he can learn about the ovals.
"Alonso wants to win races again and he can most likely do that in Indycar," Surer added.