Update: Deep Silver has issued the following statement regarding the removal of Dead Island 2 from Steam:
"Dead Island 2 is in development with Sumo Digital. Once we have new details to share, we will do so."
Better than nothing, I suppose. We'll keep you posted.
It has not been smooth sailing for Dead Island 2. In April of 2015 it was delayed significantly, which is not all that terribly unusual, but then publisher Deep Silver gave the boot to Yager Development, which most definitely was. Techland expressed interest in resuming the mantle, but that went nowhere; then, earlier this year, it came to light that Sumo Digital had taken up the reins.
But now the saga has taken another twist, noticed earlier today by NeoGAF: The Dead Island 2 listing on Steam has disappeared, and SteamDB now refers to it as simply “Unknown App 268150." Naturally, this has fueled speculation that the game has finally been canceled, although as several commenters have suggested, it could also indicate that a “re-reveal” is coming. The Steam page was based on Yager's ideas for the game, after all, and since “conflicting visions” are what led to the split with Deep Silver in the first place, it's not unlikely that Sumo Digital's creation will differ dramatically from what we've previously seen.
I've reached out to the appropriate people to find out what's going on, and I'll let you know what they have to say about it. In the meantime, remember: We may not have the game, but we'll always have this spectacularly goofy trailer.