I find these interesting facts about the congestion problem in Mexico City: the residents of the city, spend 219 hours per year in traffic, thanks to a population that has grown sixfold since 1950. Millions of people rely daily on public transportation in order to be able to move within and outside Ciudad de México. Although private cars represent only about a third of daily commutes, more than 80% of roads are occupied by commuters, resulting in gridlock that costs CDMX billions. And, pollution: Mexico City enjoyed acceptable air quality on only 26 days in 2016, the most recent year for which figures have been published. Despite all of this, México city is the main economic hub of the country (eighth richest city in the world, and first in Latin America). (info:https://hyperloop-one.com/blog/how-hyperloop-could-transform-mexicos-megaregion)
So, one of the proposed route is a connection between the new airport and the densely populated western section of the city, and a cargo link from air freight terminals to Central de Abasto. This route is expected to ease the flow to and from the airport. The project wants to integrate the Hyperloop system into the existing and future transportation hubs by locating the station near three current Metro Line stops, an intercity bus depot, and the future terminus of the Toluca-Mexico City. Following these measures I think that the congestion problem could be diminished but not entirely solved.
Another indirect benefit of the Hyperloop México is making the opportunity to travel by air more affordable for others sectors by creating a healthy competition between airlines (since hyperloop could connected two distant airports) which leads to a reduction in the prices for consumers. And at the end, additional flights at a lower price can create a competitive local economy, boosts spending for local businesses, and provides tourism and trade opportunities. This idea is related to this article: https://hyperloop-one.com/blog/creating-one-airport-out-two-hyperloop