IF (big IF) the launch is late august. Then experience with 2012 is that Arenanet has enough time to design halloween afterwards. They can also choose to put halloween 2013 (with the 2014 alterations) on another repeat.
I don’t think the mad king dungeon will ever return. The first reason is that it was never a real dungeon, but just an instance that used dungeon mechanics. The second is that it was part of the break out story that the mad king returned for the first time in 500 years.
As for SAB: Do not expect SAB being developed before the start of HoT. The main issue is that it is a Josh Foreman product. That guy is just too awesome and needed for HoT.
Arise, ye farmers of all nations
Arise, opressed of Tyria!
It really depends on what model ArenaNet is now planning to use/test. Originally they had a 1 month model, then 2 weeks, then it turned into the living story. The living story wasn’t good for marketing because people that aren’t active players don’t care. An expansion however, people notice. Will ArenaNet continue with the 2 week model or try something different? After the expansion is released, I’d expect to see 3 months of nothing, which is generally the time it takes for the novelty to wear off for the average person. At that point, I’d expect to see the living story again, running for roughly a year, broken up into 2 chunks – the end of HoT, the beginning of something new. After that, back to waiting for the next expansion (~2 year cycle).
If HoT releases prior to Halloween, Halloween and Wintersday will likely be the next updates. The normal cycle would resume in late January. What about November however? Bad timing. Maybe some other event, like a WvW tournament or something.
If HoT doesn’t release by late September however, expect to see a November or late January release.
