The developers at Treyarch have been very clear about the fact that they are just going to focus on the one map we already have in Call of Duty: Black Ops 4's Blackout mode for the foreseeable future. They've instead teased that we might see changes to the existing one, similar to what Epic Games is doing with Fortnite, and one of the most obvious examples of this has been David Vonderhaar repeatedly stating that "there's a lot of open water out there".
Well now the Call of Duty Twitter account has posted a short video showing a radar pinging the Blackout map. Most of the map looks normal, but then a small blip appears in the water north-west of Array. As the date shown in the video is December 11 we won't have to wait long before the "incoming" object will make its appearance on the map, but let's speculate while we wait.
Could it be that either the Carrier or Hijacked map from Call of Duty: Black Ops 2 is about to enter the empty water?