The Spaniard, who only chose to race at the Indy 500 because of Honda's current predicament, is in the third and final year of his contract and has made it clear his top priority is finding a auto which can challenge for a third world championship.
"He wants to win and he wants to put McLaren on a contender position for the championship". So if the calendar stays between 20 or 21, the range we know from the last couple of years, I will be happy to continue.
"I joined this project because I wanted to be champion, and we are not in that position, so if you don't see things changing, if you are not in a competitive position, maybe you change project. I think you can", he said.
"That's the only thing I can say now until I sit down with myself in September or October - after the summer, as I always said".
Honda has struggled with its engine this year, with Alonso's best finish this year 11th place, in Russian Federation. I guess for the team, and same for me.More news: White House: Trump's tweets are 'official statements'
Executive director Zak Brown has dropped the strongest hint yet that the Woking-based team are considering splitting with engine-supplier Honda after a disastrous second spell with the Japanese manufacturer, and hope to outline their plans for next season over the next three months. "After three years, we are not in that position".
He said: "Missing upgrades, and upgrades not delivering to the level we were told they were going to, you can only take that so long".
"The Indy 500 was an incredible experience and it's been unbelievable to learn a completely different style of driving, on a different circuit layout and with a very different vehicle, but I'm ready to get back to my "day job" and go racing in F1 again".
McLaren's collaboration with Honda has spluttered ever since the pair renewed their partnership in 2015.
But Brown told Reuters: "Honda's working very hard but they seem a bit lost".More news: Van strikes pedestrians on London Bridge
Until recently, senior figures were briefing that McLaren would definitely stick with Honda in 2018 but the ground appears to have shifted and there are growing indications that they may split.
The French Grand Prix will return next season - with F1 chairman Chase Carey insistent that the sport must not turn its back on its traditional European heartland - while long-term agreements with Russian Federation and Azerbaijan were put in place under Bernie Ecclestone's tenure. The Spaniard has struggled in the first five races so far this season and just when McLaren looked like they were making progress with their vehicle, things have taken a turn for the worst. Mercedes, Ferrari and Red Bull are considered unlikely to want to sign him and while Renault is keen, it also could not afford to pay him anything like the amount of money he is earning this year. Alonso's best finish this year is 11th, in Russian Federation.
"In F1, the third world championship is still my biggest priority", he said.
"I've always enjoyed the Canadian Grand Prix", added Alonso. "The circuit is unique in that it's very demanding on both the auto and driver".
But he said his performance at Indy, where he led several times and was contending for the win in the closing stages only for his engine to fail, had encouraged his belief that he could win there and at Le Mans in the future. But at another time I can jump in any vehicle, in any category, with any tyres, with any rules that I go there and I'm competitive.More news: Scott To Veto Ed Funding But Fate Of HB 7069 Still Unknown