Assuming quests are only talking to NPCs, then I could see some issues with NPC markers. But as long as they have a good variety of quests, from locating random ???s, Spawning NMs, simple kill quests, and NPC story quests, then I would be happy knowing which NPC to go to. It's better then sitting and writting down what to do next (what I did in 11 when I found new quests), to going to the menu every time you want to work on a quest (which is what we do now for 14). And, already with the current quests in 14, at least 1/2 of the quests I have done (closer to all) have had zone triggers, which will never appear as markers, you still have to find the spot.
I will be interested to see how it's implemented. Especially since I was planning on completing all rank 20 quests in the first couple weeks in march.