Barcelona decided to pick its La Liga match against Villarreal to be played outside of Spain and submitted its demand to La Liga which apparently accepted the request and sent it to UEFA which seems to accept the suggestion too and it is up to FIFA to accept or refuse it.
Since the match will be played in USA, Miami, then I suppose FIFA will not try to annoy the president especially that the big event, World Cup, will take place next year in USA.
Back to Barcelona request, apparently there is some earning that will go directly to them to fill their always empty boxes.
Barcelona just found a means to raise funds that's all. I think they have noticed how much the games that were played in the US made the teams a woofing amount of funds and they just want to take a chance at it to raise their dwindling financial condition. FIFA will have no course to reject their request because I think even FIFA is going to buy into the idea but if every clubs starts making such requests and it becomes a trend then it will no more make sense to see a country league matches taken to another country without a good reason but financial benefits.