It has been widely rumored that the FIFA World Cup™ will be held in the CONCACAF region. Now with the introduction of a 48-team competition it will surely be a tournament that will be held in a country that has an abundant amount of unused stadiums during the summer. (cough cough -> USA)

With multiple NFL teams building new stadiums (surely be done by 2026) and MLS teams expanding as well as teams building newer stadiums, its a no brainer that FIFA will want to use the USA for introducing a tournament of this magnitude. The USA will have the ability to host somewhat of a trial format allowing FIFA to gain knowledge quickly and decide to continue the newly adopted format moving forward.
According to FIFA:

The FIFA Council has unanimously decided in favor of expanding the FIFA World Cup™ to a 48-team competition as of the 2026 edition.

The new tournament format will change to 16 groups of three. Then the top two teams from each group will advance to a 32-team knockout stage. The new 48-team competition will be defined to not have a reduction in rest days and will guarantee a maximum of seven matches for the teams reaching the final. The 32-day tournament will also be kept to not increase the length of time clubs have to release their players.