The big issue is end game content, which is why ESO will likely fail. It was the same issue with SWTOR, after the storyline quests (which were actually pretty fun to play through) you basically had nothing to do. After the initial month or so, sub levels plummeted and it went F2P a little less than a year later. The model in that game is so broken now because basic features (like more ability bars, better equipment) are put behind a pay wall. I feel like ESO is going to walk a similar road, because after the initial launch numbers are going to fall as the core MMO crowd burns through the content. The only ones playing 6 months down the line are the fewer diehard fans. That's my prediction.