I think the biggest potential flaw of CoE is its almost complete reliance on players for any of these great systems to work.
Let's look at banks, for example.
Even something as "simple" as having a safe place to store your money/goods is 100% reliant on players. You want it to be secure? Someone needs to research locks/safety features. Someone needs to install those things. Someone (potentially NPC's) needs to stand guard.
Despite all that, the bank manager could still potentially just walk off with your goods.
I absolutely LOVE what CoE/SBS is trying to do. However, as Daniel said, I just don't think gamers have the maturity to handle it.
Additionally, from a different angle, what happens when key people get bored? Or take a break? Or have some personal issue come up?
Everything in CoE appears to be interconnected. What happens to the economy in a small settlement when the blacksmith disappears? Or the town sheriff decides he doesn't want to do that anymore? Or the local banker picks up and moves to a bigger city?
Yes, I am aware that NPC's will be able to fill roles to a certain extent (how well they will be able to fill those roles is still unknown). However, let's assume they will be able to do a perfectly acceptable job.
Now, you have a different issue. EVERY time you "replace" a reliable NPC with a person, you have inserted a weakness into the system. That's one more role you have to worry about. One more person you have to keep an eye on so they don't abscond with XXXX. One more person that might just not feel like "doing their job" today.
The players themselves will be what has the greatest potential to ruin this game.
However, knowing how players "are", having almost 20 years of evidence showing how they have a tendency to ruin things, and are the reason "we can't have nice things", if SBS isn't taking steps to account for this, then we might as well just check out now.
Any system that relies completely on players for it's success, with no "back-up plan" is doomed to failure. Even EVE, with all its craziness, has safe banks/hangers.