From my understanding, I thought it is a plan of revenue sharing through FIFA earnings and some through ads and ticket sales. So whichever team qualifies and advances in tournaments (World Cup, CONCACAF, International Competitions), the money paid off by FIFA gets distributed to both national teams.
To me, in some way that makes sense because the women's tournaments gets paid less, but the national team is more successful therefore they are contributing to the pie. Meanwhile, the men's team doesn't lose as much when they miss a World Cup. In terms of ads and ticket sales, I don't think the men's team is as big of a draw domestically as women's so that may also even out.
Another component is that for the most part, the men's national players are making money abroad so perhaps their loss is not as big of a detriment as a woman that may be at her best and winning but only making a portion of the men's.
I could be wrong about this but it does seem like a step in the right direction for USA's national team, mainly because the women's team is already so succesfull. I don't think the same method would work for other countries like Brazil and for FIFA as an entire organization.