OP, why you're so confident that it won't happen in a million years. I kinda feel that such thing can happen one day and it would have much bigger influence than ban of mixers. I don't know how I would react to such decision. It's not even about signature campaigns. But it would be end of all promotions from gambling websites like prediction pools, BSFL, contests and etc.
The admin would have banned it long ago if the casinos were illegal and there had been a government restriction on places where they could advertise the platform.
Same can be said about mixers - for many years everything was ok with them and one day things has changed. Same thing can happen with mixers one day if governments stance will change.