Looks like they've been wanting to branch out from the Zombie Survival genre for a while, but just didn't know how to.
Helk was meant to remove Zombies before we released on Steam. That never happened. The sooner we remove them the less people will miss them.
We don’t know whether we’re actually going to have to replace them further down the line. It’s not something we want to rush into. Reskinning them so they’re ‘mutants’ instead of ‘zombies’ goes against the whole point of removing them in the first place (which is: we’re not a dayz clone anymore).