Japan has played South Africa only once ever, so in order the give everyone 26 games, I have awarded the missing match as a 3-0 win to South Africa. Sorry, and I know that Japan actually has a 100% record against South Africa, but if they played again, would Japan win again? Anyway, as soon as this is remedied and Japan has a second game against the Springboks I will add it. Also, Tonga and Argentina have also played each other only once, and in this case I have left their "second game" as a 0-0 draw.
One of the main talking points after the latest round of autumn internationals is whether Ireland could be judged to be number one in the world after having beaten the number one in the world. On boxing rules (beat the champion, become the champion), maybe. On league table rules, no. New Zealand has got only two current defeats, against Ireland and South Africa, but Ireland, for all their impressive current doubles against Australia, England and France, have five current defeats, against New Zealand, South Africa, Wales, Scotland... and Japan. Fix that, and sure, you can be number one.
I'm not a rugby expert at all, but thirteen games seems to be a fairly doable number for each of these sides to play every year, so why not play each other once a year? The Northern Hemisphere already does it in the Six Nations tournament and the Southern in the four-team Rugby Championship, so why not add four more teams (Samoa, Tonga, Fiji and Japan), and play it as a single global round-robin tournament? You wouldn't even have to scrap the Six Nations or the Rugby Championship: they could still be played inside this whole tournament, in the same way that the Calcutta Cup, for example, is contested as part of the Six Nations. After tallying all the results up, you can still give awards for the best team in each Hemisphere and proclaim a Six Nations champion, a wooden-spooner, etc. Also, you could introduce promotion and relegation, so that the 14th team changes every year. As the table stands, that's bad news to Italy, but hey, maybe you could soften the blow by having the bottom team play off against the best from anywhere else in the world for the right to compete among the best the following year. Meanwhile, the remaining 13 teams could be using that play-off international date to play one team each outside of the Top 14. If rugby really is serious about developing other nations, nothing does more for the cause than inviting the best in the world to play against those other countries just bubbling under the surface. The kids attending those games one day will be answering questions in the future saying that they really got their desire to play rugby on that day when New Zealand, or England, or South Africa, came to play my nation and I became hooked.
So, does rugby have 14-15 dates a year to play internationals? That's for them to decide. If not, maybe the top division could be trimmed to 12, but that would mean losing a couple of deserving teams every season.
As for logistics, especially travelling and venues, that's for someone else to decide. Maybe small groups of three or four so that over 12 days they play one another at one of the participant countries? For example, England, Japan and Australia playing in Japan, while Scotland, Argentina and South Africa play in South Africa, while Ireland, Fiji and New Zealand play in Ireland? Something like that. I know that matches involving the smaller Pacific teams (Tonga, Fiji and Samoa) are difficult to organise due to a variety of issues, both economic and otherwise, but if there is a will there will be a way. The Six Nations and the Rugby Championship have got big because they have been doggedly playing every year, and the World Cup has captured everybody's imagination in a very short time of existence. If this idea is implemented with vigour and insisting on it every year, it will become great very quickly.
Current results for this table (up to Monday 26 November 2018):