The frustrated two-time world champion has been making noises all season about quitting the British team, who are widely expected to dump their misfiring Honda engines and go with Renault instead.
Alonso's car has failed to complete six races this season, and his best finish so far is sixth. He said he had "many options" both inside and outside of Formula One, but added that "very good news is coming".
"Whatever I do next year is because I want to win. I will not be around in any series to be fighting for top 10 or top 15," he told reporters ahead of the Singapore Grand Prix.
"There are many options out there that I'm looking at. Formula One is my first and only priority so I will wait to make a decision on that before making decisions on other series.
"At the same time I want to give time to my team. After the last three years, the struggles we went through together, to have time for them to make decisions, to see the future, next year's car. And after they take decisions I will take mine."
Alonso's comments appear to hint that he will stay at McLaren next year if they axe Honda, which is strongly rumoured to happen before Sunday's race.
Alonso, 36, is one of the oldest drivers on the grid, and he also hankers after becoming only the second man after Graham Hill to complete motorsport's Triple Crown -- winning the Monaco Grand Prix, Indy 500 and Le Mans.
- 'Game of chess' -
Alonso last year skipped Monaco to race the Indy 500 but he seemed hopeful that he would contest the famous street grand prix next season.
"If I remain in Formula One it is because I can believe that I can win next year. So that will make the decision a lot easier because I will be in Monaco because I won't want to lose any points," he said.
"The priority is Formula One... And the Triple Crown is in the background. I'm waiting for my current team to make their decisions and after that, to negotiate."
He added: "For my fans and for motorsport lovers, they will have a fantastic 2018 season. The plan is ongoing and very good news is coming."
Alonso last month denied telling McLaren he'd quit if they don't ditch Honda. Multiple reports say Honda will open a partnership with Toro Rosso, whose driver Carlos Sainz is tipped to join Renault as part of the deal.
Sainz said he couldn't comment on the rumours but he added: "My ambition is to try and be a world champion one day. Whatever path there is, I will take the shortest path."
World championship leader Lewis Hamilton, who has won two of his three drivers' titles since leaving McLaren for Mercedes in 2013, said: "Formula One is like a game of chess.
"It's really about picking your moves at the right time and hopefully you have enough options.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)