Probably save to assume that they will keep selling half a season of Living World once a year for an almost full full box price, but I’ll wait until something is actually released. Maybe it’ll be more than 85% cannibalized and recycled mechanics and art assets.
I’m not sure whether this is entirely true or rather whether this is true for the more casual MMO player. You are describing the traditional Until Death Do Us Part way of playing MMOs. But GW2’s (mostly) lack of vertical progression makes it really easy to return to the game after taking a break or playing something else (another MMO, e. g. GW3), without feeling that you have missed out on a lot.
By the way, this is one of the things I do not like about the new daily system (wizard vault), because it kinda discourages playing something else or taking a break, unless you are able to …