I am all for encouraging new features that Team Hashnode intends to offer us, however...
To be completely honest, I'm not a fan of competitive challenges in friendly communities. It all depends on how you plan to go about it.
I would rather see something like a Workshops section added, which would feature Tutorials w/ Challenges used to review the material learned. Adding an educational slant to the idea of code challenges would give it a much more solid foundation, imo. Then, maybe at that point, random code challenges can lead the user into the workshop it's related to.
That's also something I don't see as much as I'd like to, which encourages collaboration through education.
Either way, I'm always looking forward to the new ideas Hashnode will be presenting to us as it grows and evolves.