The Pentagon spends in 36 hours what the UN spends in a year.
Don't think the UN will be calling any shots anytime soon.
More likely is an enhancement of existing human rights legislation preventing harmful mental abuse of minors.
A new classification of 'high control group' <aka dangerous cult> with specific legislation would allow mainstream religions to continue unaffected.
For example, taxing HCG's differently to other religions and preventing formal association <baptism> into HCG's for minor children would be a big step.
An increased focus on Health and Safety legislation could slow down their volunteer recrutiment program <aka preaching>.
A successful lawsuit proving that the WTS caused wrongful death by coercion and offering misleading medical advice could make whole blood and primary components a conscience matter. (97% done already)
Just some examples of where 'politics' and the legal system can change the WTS in something more palatable.
Personally I think religion is an anachronism that is in long decline in any case, with or without acceleration from government. It is fundamentally out of step with the major trends affecting humanity in the 21st Century.