I'm not against the idea, but I'm wondering what's the trigger for non-child-havers? Or is it just the idea of a sabbatical?
On a sidenote, what's the terms on parental leave? How soon after one can you take another? If you're popping 'em out quick as can be, is it months off every 12 months?
That is a really cool idea. I think the problem is it's just a bit too niche. A good portion of the people intrigued by the narrative and world-building might get stymied by the travel simulation (I'm envisioning both flying and sailing) and the simulation nerds might just skip past the text and story to get back into flying.
It's certainly something that an indie dev has to shoulder for pure passion of seeing an idea come into the world, and that requires an idea that grabs you. Targeting it as an underserved market will only backfire.