Ah, Phil Pickering! Great to see you here and you would be the one to throw in the Big Question.
I'm not @ryan or @zsims or someone who'd call the shots here, but here's my 2¢ for what it's worth!
Codecademy's mission is to
teach people the skills they need to find jobs. When thinking about how we may evolve going forward, that's the biggest thing I'd keep in mind. Follow-up questions would be "what are the gaps between what we teach and people finding jobs" and "what types of jobs are we training people to get." When we're thinking about how we move forward, those are the things we have foremost in mind. You mentioned this yourself, with saying "once you've completed those courses there's the big question of where to go next" - this is something that we can not only answer through things like AMAs and blog posts, but through our platform itself. Projects are a big part of that agenda, but there's more that we can do.
This is all a roundabout way to say that more advanced courses that go deeper into technologies will have to be on the agenda, not necessarily because they are "necessary" to get jobs, but because at the very least they'll help people to feel more prepared to find jobs. There are a plethora of languages out there but there's a relatively small subset of those that are more useful in terms of getting a job, and particularly in getting a job in fields in which we're strong - web development. We're likely to focus on those before making a much broader library of content, although a broader library would be helpful too.
I know this is a way of answering your question without really answering your question but I hope it helps give a sense of how we're thinking here.