The two-time title holder is out of agreement toward the end of this year and there are different assumptions as to where he will choose his next stoppage.
In the midst of McLaren-Honda's debate, Alonso skipped Monaco Grand Prix a weekend ago to contend in the Indianapolis 500 and admitted he could be moving one year from now.
In a recent interview, the Spaniard has opened up about the situation and admitted he has no solid plan for next however he is almost certain that he won't join Red Bull.
He cleared Mercedes and Renault could be potential outcomes but a switch to Red Bull is not likely as Max Verstappen and Daniel Ricciardo both are long term in a long term with them and the authority prefers giving chance to young racers.
"We'll see. I would be lying if I told you now that I have a concrete plan," Alonso told Planeta Calleja.
"I could go to another team - I don't know whether it is Mercedes or another. If Renault starts to dominate, I don't know. If in June or July a team calls, I think we would have a chance, but it's all to be talked about."
"I think perhaps Red Bull is the only one that has doors a little closed because it already has young drivers with long contracts."
However, Alonso additionally ruled out hanging his boots as of now but suggested his future could rely on upon F1's new possessors Liberty Media. If the group plans to expand total races beyond 20, the racer may then change his mind.
"I have to see what they plan to do," he said. "I read that they want to make a championship of 25 races. When I started in F1, there were 16 -- now there are 20. If they tell me there are 25, I will retire."