Thirty-two teams contested this year's World Cup in Russia, widely feted as one of the most entertaining editions of the modern era.
Although FIFA is intent on 48-team future editions of the World Cup from 2026, a decision on Qatar won't be known until next year.
"We'll decide in March," Infantino said Sunday on French TV show Telefoot.
"We've already decided that future editions should feature 48 teams, we all think it's a good idea."
When the next edition is held in Qatar, it will be the first to be held in the Arab world and the first in a majority-muslim country.
Due to the soaring summer temperatures, it will be held over November-December instead of the European summer months of June and July.
As a result, the competition has been shortened by three days -- a factor that could be decisive in the considerations on the 48-team format.
"It's not easy because it will be played over 28 days, instead of 31 for a normal World Cup," said Infantino.
In March, FIFA will hold a meeting in Miami, where it could also decide whether neighbouring countries could be allowed to host some of Qatar 2022's games.
"Why not, if it's feasible ?" added Infantino.
"We're talking to Qatar about the possibility of holding some matches in nearby countries.
"Why not dream, it's not impossible."