I'm guessing from 2018-2021 we'll have the regular tournaments such as
- European Championship 1,2 &3
- Pacific Cup
- Americas Cup
Plus Pacific Island and African teams will surely get visits from English & Australian teams.
The big if is just Australia, NZ & England from this report and what they're going to do in the inbetween years.
I suspect it will look like this
Y1 - NZ Tour of England
Y1 - Qualifying for Federations Cup
Y2 - Federations Cup 8N
Y3 - Australia Tour of England
Y3 - RLWC Qualifiers
Y4 - RLWC
Repeat
All played post season
In season schedule will depend of the success of SOO on a standalone rep weekend