It looks like the cover star for WWE 2K18 has been leaked before an official announcement. A Reddit user who has leaked what will happen on WWE shows before they air revealed that Seth Rollins will be the cover star for the latest installment in the WWE 2K games series.
Here is a screenshot of the Reddit post. The reply was in response to a thread that asked “Who will be WWE 2K18 cover athlete?”
With the users post history being 100% accurate with leaks, it’s very likely this is true and that Seth Rollins will be the next cover athlete for WWE 2K18. You can expect an official announcement in the next month as that is when they are usually officially announced.