Dietrich Mateschitz is considering pulling Red Bull and Toro Rosso, who are currently without an F1 engine supply for next season after parting ways with Renault, out of the championship.

Should that happen, and with Haas joining the fray, the Formula 1 field would drop to 18 in 2016.

Mercedes chief Toto Wolff likes the idea of introducing third cars, but as a measure to boost rather than maintain the size of the grid.

But Button told Autosport: “If they have to introduce them, they have to introduce them.

“All the top teams who are able will put a third car forward but at the moment, we hope that isn’t the case.

“We hope we will have a full grid in 2016.”

When it was put to him that the introduction of third cars would allow teams to run young drivers, Button said: “No, other categories are made for younger drivers, not Formula 1.

“Third cars should be introduced if they are required for a full grid.”

The dynamic of a Formula 1 team would change should the championship introduce third cars, with each driver having two team-mates.

“I’ve never thought about what it would be like to be honest,” said Button.

“Ultimately, you always go out there to be the best, to be the best in your team so nothing changes really.

“You just do your job as normal.”