.....
I also believe fairly strongly that the 'simple' interpretation of what Gates said (through his disgusting smirk) is the accurate one. Vaccines will kill a ton of people, and make the rest into a kind of Idiocracy which is easy to control and which poses zero threat to the rich and powerful.
That presumes there is someone other than idiots in the Idiocracy. At least in the movie, there was not, with the exception of two from the past.
We're certainly not seeing evidence of any rich and powerful who are much of anything but idiots.