I agree with NewChapter, there would need to be some conditioning first. Something like:
"This world is going nowhere and is best left to Satan and his followers. Dear brothers, we wouldn't have to tolerate the machinations of the devil, we can simply wake up and be in paradise. It would be much easier for Jehovah to destroy all those who chose not too heed his message if his faithful followers were not among them. We don't have watch our loved ones suffer at the hand of persecution or be under further pressure ourselves by the independent spirit of this world that has already taken so many of our dear brothers. Over the next few weeks we will consider a special brochure for the congregation bible study entitled, "Enjoy The Promise of Everlasting Life NOW". Each baptized publisher will receive a copy at the start of each bible study session and it will be collected at the end of each session."
After several weeks of conditioning, I think 70% would drink it. For most of those folks it would be due to peer pressure. Who wants to look like they don't trust the slave, I mean, Jehovah? The 30% of folks that don't drink it would be primarily comprised of JWs from first world countries.