Avengers: Endgame comes out in North America next week, and the whole continent is beside itself with anticipation for the grand finale of modern pop-culture's tentpole franchise. Understandably, people are looking for whatever little hints of Marvel they can find in almost everything, both out of sheer excitement, and in an attempt to capture some of the web traffic generated by said excitement. This fervor even extends to the world of Fortnite, where the rumor mill is churning over the possibility of Thanos' return to Battle Royale.
A tweet by Fortnite datamining operation Skin-Tracker featured screenshots of kill-feed lines uncovered in v8.30, and while Skin-Tracker's goal was to point out a new line where one player "unleashed an inferno" on another player, Twitter folk immediately glommed onto Thanos' kill-feed text, which was also in the list. This has been interpreted as proof that Thanos will return in an update to coincide with the release of Avengers: Endgame, and we see how people could arrive at that conclusion. Personally though, we're not convinced.
It's very likely that this kill-feed text is just leftover from Thanos' original Battle Royale event, which took place during the release of Avengers: Infinity War. Epic would have no incentive to remove this code from the game, as it would never be displayed so long as the Infinity Gauntlet was disabled, which it currently is. Paying a developer to remove that code from the game would be a waste of resources, since that developer's time would be better spent on upcoming content, or error resolution for issues that players actually encounter.
The code shown in Skin-Tracker's tweet also mentions the Infinity Blade and Kevin the Cube (RIP Kevin), which serves as further proof that these are simply vestigial entries in a master list of kill-feed messages that Epic never needed to cull. We're not saying that Thanos definitely won't return, mind you, but all this tweet proves is that some of the Thanos stuff from 2018 is still in the code.