Hopefully, informed people. Unfortunately I don't have a definite answer to your question but that does not make "the market" a valid one (maybe it is, though I don't think so because I don't trust people for making decision virtuous for the community through individual ones, there needs to be something more clever and functional).
Well I ask because in my mind it is simple: individuals decide for themselves what is virtuous.
Of course as a side effect this is reflected in the market, as individuals engaging in things they find virtuous are reflected in the market.
If you don't trust people to make decisions for the community, why not just let them all make decisions for themselves and nobody else? That would solve that problem, no?
For any given decision, letting individuals decide what they want does not necessarily lead to a great situation for the community. Climate change-related stuff comes to my mind. We are failing to take the right decisions, and have been for decades (in my opinion). I often see people say "let the market decide" as if it were the ultimate way of deciding what is best. It's often not in my opinion.
For the topic at hand I don't think there's a good way around letting people pick what they want to study among what is available. I deeply believe they should be able to decide what they are going to study for themselves and be given the keys to take informed decisions. Nobody can know better than themselves what is best for them.
You still need to provide a sensible set of available curricula, and people don't individually have the power to decide which curricula should be available so you still need an informed group of people to decide on this, not individually. Obviously you'll probably have to close curricula which don't attract enough people so you'll have some bit of market deciding.