The 2008 world champion's current deal includes 2012, but it emerged last week that a success-related break clause could open the door for a switch to Red Bull.
However, Christian Horner on Saturday estimated the chance of a Sebastian Vettel/Hamilton lineup next year as "slim to nil", at the same time as a frustrated Hamilton was publicly laying out his demands for a new deal at McLaren.
"When I re-sign the contract with McLaren they are going to be shocked at how many days they are not going to be able to make me do," Hamilton told reporters after qualifying tenth near the end of a demanding pre-Silverstone media and sponsor schedule.
"I will be doing a lot less work. There is definitely a danger of burn-out," said the Briton.
Hamilton, who has had a poor run of results and been the subject of intense speculation as well as criticism recently, admitted he is looking forward to F1's August break.
"It is nice to know I have got that coming up," said the 26-year-old, admitting he feels "older" than 30. "Am I tired? Um, maybe. Have I trained? No, never trained for the past two weeks.
"But what's important is that the sponsors are happy," he quipped.
The comments mean McLaren's PR machine might need to roll out again in the wake of the British Grand Prix, particularly as Hamilton has reverted to pessimism about his chances of success.
"I think we might have run out of miracles," said the Briton. "I think I drove the car as well as I could. It's going to be a long, long season."
Even his McLaren crew did not escape criticism.
I drove the car as well as I could. It's going to be a long, long season
"It was a poor performance," said Hamilton after qualifying tenth. "I can't see the weather forecast from inside my car but I kept asking my guy 'What's the weather doing?'
"Everyone else went out on new tyres, while I was out on old ones."
But even team boss Martin Whitmarsh admitted that the championship is no longer the main focus.
"To say we are concentrating on winning championships would be the wrong focus. We have to concentrate on winning races again," he said.