As far as I'm aware, the possibility is *zero* because there is no individual or company to file a lawsuit against.
Ehh.
Okay, so first off-- you're absolutely right on one point: Even the real Satoshi wouldn't have a legal leg to stand on. But not because there is no one to sue... but because there is nothing valid to sue over.
But not having a legal leg to stand on doesn't matter that much if you have a supply of money to keep litigating. You can sue anyone at any time for essentially any reason. Your lawsuit, if frivolous, will eventually fail but not after costing the victim a lot of time and money.
Wright has already filed a pile of frivolous lawsuits, -- he keeps losing them but they still cost their targets money.
Wright could sue anyone, he could sue you. If he was effective he'd manage to use the publicity of doing so to bring more victims into his fold and make more money out of it than the cost of the lawsuit, but presumably even if he's not effective he could keep it up for a while on the largess of his existing victims.
Now, none of this would stop Bitcoin itself. ... But on the other hand, if he kept suing anyone that does anything important for Bitcoin and as a result scared off people it could still have a negative effect. Unfortunately, the legal systems in the developed world seem ill prepared to handle a lot of the fraud in the cryptocurrency ecosystem and Wright is a great example of that.
Wright's frivolous litigation probably won't stop anyone that has a healthy business-- if you're making money you can afford to swat the wright-fly as a cost of doing business. But enthusiasts that participate because they love Bitcoins social or technological implications? Journalists that have razor thin margins? Some of them-- perhaps many-- will find other things to do rather than be targeted.
I've already heard from a number of people, including fairly high profile journalists, that they're avoiding saying anything about wright (or, even, avoiding retracting stuff they previously published which they now know to be false) because they're concerned about frivolous litigation by wright.
And that is, of course, exactly what he wants. It's expensive for him to sue people, so much better if he can spend a few minutes throwing around a bunch of baseless threats and then a large number of people well self censor.