The 34-year-old flanker, who has made 142 appearances for his country, was given an emotional send off last month as New Zealand beat Australia 41-13 in Auckland – a match billed as his last home international.
“I haven’t made a final decision yet although I’ve given a reasonably strong hint,” said McCaw.
“Whether I play much more past this year is pretty debatable, but the reason I haven’t made any announcement is I really wanted to play this year, and this tournament, like you would any other year, as if you were going to play on.
“With the door still being open, that decision is going to be made later. I want to make sure that when I turn up for training, I train to be better than I was the week before.”
McCaw captained New Zealand to victory at the 2011 World Cup and his side start the forthcoming tournament, which gets underway on Friday when England play Fiji at Twickenham, as favourites.
“That type of expectation is what has driven the All Blacks to keep training hard and to give their best,” added McCaw, who is set to lead New Zealand in their opening fixture against Argentina at Wembley Stadium on Sunday.
“It can be rough at times but that is just part of being an All Black. I’d hate for that to change. That’s what you want. You want to go out and win every game. You want to do everything right so that you can give yourself a chance.”