It's stated that there's been delays on various projects. Anet said they're going from living story 4 straight into 5, which really should have been the time for the next expansion, so it's possible the expansion is one of those delayed projects. Much in the same way legendary weapons 2.0 were all delayed, and still being released one by one 4 years after the expansion it was suppose to come from. I've always suspected there was a lot of mismanagement in that company for a long time, especially hearing they had maps laying around not completed and probably never to be implemented, they had 15 unused pvp maps at one point.
For a long time they've only focused on selling skins to the whales in the pve side of the game, while letting the rest of the game go to waste. Dungeons were abandoned from day one, wvw had massive potential but ignored for years until it tanked in HoT and they had to actually pay attention to get players back in there, then went back to ignoring it again until they needed to shove mounts in to get some cash, gee wonder why that isn't well received by the wvw community at this point.
Their communication and marketing departments are terrible, wouldn't be surprised if it was one person running both.
Stream for this week's big announcement is now delayed without notice, or maybe they forgot about it just like they usually do for anything wvw in the name.