For whatever reason the mideval fantasy design trope seems to work well for Nintendo. Who knows why.
I would suggest maybe something akin to an action oriented take on Fire Emblem/Zelda but perhaps go a little darker/edgier with it.
Uncharted took a while to gain traction with Playstation owners even as well, it's not like the first game was an immediate hit, it was more of a slow burn, and then the second one really broke through, but Nintendo is not that patient with new IP.
Either that or I'd suggest just buying the James Bond franchise rights, since no game developer has them anymore. I imagine at this point Nintendo could scoop in and grab them for cheap. Character wise he's a good fit for Nintendo, undeniably "cool", but not so violent that parents disaprove (because everyone's parents grew up on Bond too). That's kind of the balance Uncharted strikes as well. Plus it looks like the movie rights might be moving away from Sony, so that's another plus for Nintendo, lol.
