After a pretty successful start, things have certainly slowed down for the Dead Island franchise. We have not heard much of the game ever since it was announced that Sumo Digital was going to take over the game.
The latest rumour suggests that it might take a few years before we get to see the game because the developers are working from the ground up. It is believed that Sumo Digital has decided to start from scratch when they took over the game. That means a new story as well as new mechanics for the game.
We do not know why they wanted to start fresh instead of continuing from where the last developers stopped but some fans think that it is because Suma Digital did not like what they saw.
The last we heard, the game is still being developed and Deep Silver is confident that the game will still happen. If the game turns out to be great, most fans would not mind the wait.