In regards to the OP, what do you mean by "have left"?
Have left to what?
To grow in numbers? Probably not more than a year or two. They're very rapidly approaching stagnation.
To decrease in numbers? Probably not more than four or five years. Their methods of recruiting outsiders has seriously been curtailed by their reliance on directing people to their website and by their cart ministry. And 2/3 of their children leave the organisation. It won't be long until they have more leaving the organisation than joining it.
To change their tactics? The Organisation has always been transitory. What it was ten years ago it won't be in ten years from now. Hopefully part of their future changes will be getting rid of the two witness rule for rape victims and mandatory reporting to the authorities when there may have been a crime committed.
To be profitable? All indications are they are spending more than they can afford and are taking dirastic steps to try and decrease their overhead. It may be some time before they are able to turn a profit again - if ever. Right now they're cannibalizing their assets to stay afloat.
To admit they've been wrong about every prediction they've ever made? When pigs fly.