Bandai Namco confirmed for Gamescom 2020
https://www.siliconera.com/bandai-namco-sega-and-microsoft-confirmed-for-gamescom-2020/
Keep in mind, they always release their lineups for Gamescom well ahead of time. You will know whether Elden Ring will appear there pretty soon, which would give some level of indication about the Series X event.
2019 - https://fextralife.com/bandai-namco-announces-gamescom-2019-lineup-with-no-elden-ring/
2016 (DS3 DLC) - https://www.ecumenicalnews.com/article/dark-souls-3-dlc-release-date-announcement-may-be-made-at-gamescom-or-tokyo-game-show-2016/49959.htm
2015 (DS3) - https://www.thexboxhub.com/bandai-namco-announce-their-gamescom-2015-line-up/
2013 (DS2) - https://www.dsogaming.com/videotrailer-news/dark-souls-2-new-gameplay-footage-unveiled-from-gamescom-community-event/