One of the things that sets the original apart from a lot of other open world survival craft games is that it was designed to be a single-player experience. Hopefully they can make it work well for both solo and co-op, but that's a tricky balance.
One thing I'd really like to see is for creatures to be able to damage structures, and to balance that by having defenses to protect those structures. Being able to throw together an invincible fortress in seconds made some of the dangerous areas a lot less threatening.