The final format for the 2020 New Zealand Sevens was yet to be finalised given the challenges around hosting the men's and women's draws over two days, Cass said.
"We are working with World Rugby to establish the best format for all of our stakeholders and are confident we'll deliver another great experience for players and fans."
Cass said NZR were talking to World Rugby and the Fiji Rugby Union about hosting the event in Fiji during the 2020-2023 cycle.
"Everyone has seen the contribution of the Fijian rugby community to the success of the tournament in Hamilton both on the field and in the stands. An option being looked at is alternating the tournament between Hamilton and Fiji and early negotiations are promising."
Fiji Rugby Union Chief Executive John O'Connor said it was an exciting time for Fiji's rugby community.
"We are grateful to NZR for offering to alternate the hosting of the HSBC New Zealand Sevens with Fiji and we're confident of delivering an amazing experience for everyone involved.
"Fijian fans would undoubtedly turn out in their thousands to support the tournament and we believe large volumes of overseas rugby fans would come along to experience Fiji's hospitality and passion for Sevens rugby."