This game has taken way too long to come out/go into open beta. I've followed the thread this entire time. The hype was there a few months after D3 since that was a disappointment, but now D3 is actually a good game with the patches and loot balancing. This has taken too long, I honestly think GGG blew it. The revenue model is going to be a challenge for them as well. Character and bank slots aren't needed, they give you plenty right off the bat. So all that's left is cosmetics, which is a weak base if that's your foundation for your F2P model. Take into account the character models are fairly small/thin, so seeing the detail on them isn't that easy unless you zoom in but nobody plays zoomed in.
Here's my prediction: GGG will add something controversial to the game that will help them get revenue. It won't happen right away but it'll happen a little down the line once they realize there's no steady income stream. I'm thinking a RMAH could be added in the future, which would be funny since their community is so against it, but it may be the only way PoE can survive in the long run. Literally the entire game is free in its current state.
You are assuming that people play PoE because D3 is mediacore game. That is simply not the case here. D3 main problem is that it's not Diablo game like people wanted where PoE is spiritual sequel to D2/D1.
Frankly balancing never was Diablo3 issue since there was no PvP. No proper leveling, shit loot, RMAH, int/dex/str stats/, shitty story, No PvP, no ladders, spellcasting with hammers, DPS fest, junk affixes for items and many more things makes this game mediacore at best.
They can't fix most of those problems because it is how games is created. Sure fighting animation/physic is fun but this alone don't make a good game.
This points that people will stay with PoE and they will play it.
As of money it's 20 people studion they don't need xxx milions like diablo3 to recup their credits. From their backer program they earned 5mln$ which Chris stated that is a lot of cash for them. And you clearly have no idea how much people want to buy things that will give them opportunity to change their look (look > HOME)
Also if you look into their forum and various interview you will see that they are bunch of devs which know what to do with their game and game quality is 1st priority above all things. They changed release date from december to january because they didn't want D3 premiere thing (meaning errors)
As of GW2 model i will ask you this way:
Which generated more income ?
1. LoL
2. GW2
Now consider that PoE is awesome game (which really is) and you will see that this game will be played by ton of people.
Diablo 1/2 would not be hit classic if they were not good.