It put Fonterra in the best position to deliver the value outlined in the co-op's strategy, while also protecting farmer ownership and control, Rivers told The Country Sport Breakfast's Brian Kelly.
It was important to change Fonterra's capital structure as it allowed the co-op to focus on New Zealand milk while remaining an attractive option for farmers, Rivers said.
"The Co-op's future success, it really depends on our ability to maintain a sustainable milk supply in what is an increasingly competitive environment, and one that's changing all the time - environmental pressures, regulations, alternative land uses, and lots of other things."
While farmers left Fonterra for many reasons, the most influential was the high level of compulsory investment required to be part of the co-op, Rivers said.
A capital structure with flexible shareholding would also help level the playing field with competitors - many of whom were foreign-backed and didn't require farmers to invest capital.
Protecting a strong, New Zealand farmer-owned co-operative of scale was in the whole country's interests because Fonterra's scale efficiencies helped deliver value to all Kiwi communities, Rivers said.
"For example, our milk price, it actually sets the benchmark for prices that kiwi dairy farmers are paid for their milk, so even farmers who don't supply the co-op actually benefit from it.
"And of course, our profits are kept at home for the benefit of New Zealanders."
In fact, this season's current milk price would see almost $13 billion flow back into regional economies through milk price payments, Rivers said.
Fonterra farmers will receive their voting packs on Wednesday next week and the voting period opens on Thursday, November 18.
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There would be a special meeting on December 9, immediately after Fonterra's annual meeting.
A successful farmer vote would not take effect until the Board was satisfied that any steps necessary for implementation had been, or would be completed, Rivers said.
"We are aiming for 1 June 2022, but of course we have to keep working with the government on what the changes might mean under the Dairy Industry Restructuring Act (DIRA)."
At this stage, the Government was unable to support DIRA changes to facilitate Fonterra's proposal, but it wanted to work with the co-op to reach an outcome that worked for both parties, Rivers said.
Fonterra was confident there would be a regulatory framework that supported the Flexible Shareholding structure, Rivers said.
He encouraged all Fonterra farmers to keep an eye out for their voting packs next week.
"Ensure you have your say on the proposal by voting."
