I'd still say that it wouldn't be a good idea to mandate specifically Spanish as the foreign language requirement. If people have no interest in a particular language, forcing it on them isn't going to help them learn it.
If we lived in a perfect world, I'd suggest that more languages be available in the US education system, not just Romance languages and German, which is what was available at the high schools here. It would probably be a good idea to organize language classes to be online, with some sort of access to a digital library of learning and native level media in that language.
I've definitely used Japanese more than I've used Spanish, and that's with being mostly self-taught for the 3 years I've been with the language, minus the classes I'm taking now to help refine it.
I even see more use for Mandarin in the future, seeing that the vast majority of my classmates at the moment are Chinese and some sort of desire to communicate to them besides using Japanese.