The fact they both enjoyed seeing the Westworld trailer ahead of Ready Player One could mean the official trailer could be paired with a major theatrical release.
Unfortunately, Avengers: Endgame premieres after GoT returns, but there are a handful of other worthy films worth pairing such an event with.
Bottom line, it does appear that an official trailer for Game of Thrones Season 8 is coming, although neither showrunner has given a clue as to when that may be.