Whether or not they can do it as a proper rebel league might depend on the contracts they've been signing - I wouldn't be surprised if at least some of the higher value players had a clause contingent on world rugby approval, or whatever else they needed to ensure ongoing eligibility for their nation. If they lose a decent chunk of them it's unlikely they'll be able to make up for it in time for their end of September deadline.
If they try again next year which seems more likely they may still get up, but with a lot of spent momentum this time around they will probably have a harder go of it even without the world cup. Players/agents will be skeptical, and other pro teams and competitions will likely be much better prepared to face the threat. That article also suggests that player transfer fees my end up being enforced here ("compensation for clubs") which would probably see costs balloon pretty quickly. Some of these questions might be hard for them to answer too - how do they fit with the two different test schedules for men and women for example?
I wouldn't be surprised to see them come back with a less ambitious model to try and get it started, but I can't see how this is anything but a major setback for the competition. Maybe not lethal, but it'll be a monumental effort to keep both investors and prospective players on the hook for a years time.
