I reckon that when early A380s start to be returned to lessors around 2020, we're going to see a massive drop in value, resulting in a situation just like the A340 where mid-life perfectly good A340s are worth ~20% of their original purchase price.
Lessors will see this and not buy any more. THAT is what will kill the A380.
As Dave Reid says, the A340 comparison is irrelevant. Yes used values will likely be lower than Airbus may wish because the secondary market is not yet defined. But the core major conurbation to major conurbation market (summarises the core market better than "hub to hub" as, thus far, that means just Emirates / DXB) is growing inexorably and when operators see they can lease 500+ seats for $600k/m i.e. less than a used 773ER, some will be persuaded and then some others won't want to be left behind. So the used market will develop. And the original operator of those aircraft will replace them with new, more efficient, A380s whether neos or not. It'll be slow but it'll be steady: 2014 not withstanding.
As for lessors, the A380 is just not a lessor-friendly aircraft and nor was the 747 - although that will change when it comes to acquiring used aircraft for lease into the secondary market. ILFC quickly shed their early commitments and the jury's out on Amadeo - I'd be very surprised if their order is truly speculative.