You won't get a dev answer on this because it is against proper business code.
However, I will say this:
1. 20 quests for each level seems to be the magic win amount. So until there are 20 quests each for levels 1 through 29, then you won't have a full endgame.
2. No way to expand the end. However Reincarnation, Elite difficulty, and Champions are all parts of this. I would imagine that Sentient weapons will be too, and I am sure there will be another tier or expanding to the destinies to fill out that level 30 spot. Like a destiny capstone.
3. Tons of lowbies everywhere. Moreso on the default server. I have seen guilds all over sarlona getting new members and have seen plenty of mid level players who are new and do not have a guild yet. SO gains all around.