Racing for BMW last season, Kubica found himself leading the drivers' standings after his win at the Canadian Grand Prix.
The Polish driver, though, fell out of the running for the title at the penultimate race of the season with many claiming it was largely BMW's lack of progress that cost him rather than his own ability.
This year, though, former F1 commentator Walker believes Kubica could be in the running thanks to the sport's new regulations.
"Nobody has got the faintest idea what's going to be happening in 2009," Walker said.
"They've thrown all the balls up in the air, we've got KERS, we've got slick tires – thank God – all sorts of different things happening next year. It's going to be very different.
"Ask me who will win the Championship this year. Robert Kubica in the BMW.
"They're a mighty switched on organization, BMW, they make cracking road cars and I am full of admiration and respect for what they've done. And they will get better."
As for Renault, Walker believes the 2005 and 2006 World Champions could find themselves winning more races with Fernando Alonso.
"They got it wrong by not stretching the rules as much as some of the other teams may have done in the engine department last year, but now that's being put right," Walker added.
"I think Renault are going to be a big threat, particularly with Fernando Alonso at the wheel because he has still got something to prove." Sky Sports