Dead Island 2 is definitely coming, Deep Silver has recently confirmed.
Deep Silver took to Twitter to respond to a naysaying fan who told another, “Give up, man. It’s not coming. Just move onto Dying Light.” The studio responded with, “We wouldn’t be so sure about that!”
The publisher...
I want to say it's one to one, but in all honesty I'm a bit fuzzy there. I can recommend JoyFreak's sister site AdminIntel - Admin & Webmaster Resource where there are lots for people of varying degrees of expertise with development, you likely can get a far more precise answer there!