It should be. From the tea leaves posted in this thread, it looks like the game is moving to a standardized four week rotation for all events in the game, with 13 rotations in a 52 week year.
If we assume that after this week’s Guild Wars ends, the new schedule rotation starts, the rotation would be:
Week 1: Raid Boss + New Faction Weekend
Week 2: Guild Wars + Bounty Weekend
Week 3: Invasion + New Class Weekend
Week 4: New 4.1 Event + Vault Weekend
Four types of weekly events + four types of weekend events equals a “monthly” schedule going forward. The only real question is whether this rotation is generally locked in stone, or if the weekend events can be rotated around at the devs’ discretion. Gut feeling says it’s fixed, as bounties, classes, and factions are known to be once a month occurrences.
So, looks like the future schedule is pretty much locked in stone to me.