Comment: Amazing season lifts bar to new level for Joe Schmidt's Ireland
Even Joe Schmidt admitted that he is "intimidated" by following 2017/18.
Coming on the back of a November clean sweep and a third Grand Slam, this series win in Australia rubber-stamped Ireland's status as World Cup contenders.
Off-field controversy means nobody could reflect on this as a 'perfect' season for Irish rugby, but while the IRFU have work to do on the game's reputation, the performance side of the house are delivering in spades.
Fifteen months out from the big kick-off in Japan, this June was a crucial month for assessing the runners and riders for the Webb Ellis trophy and while Ireland stood tall there is reason to suspect that they are not the only ones getting their houses in order as the four-year cycle pivots towards its end-game.
Nine matches remain for Schmidt between now and the first warm-up game and while a busy November will necessitate squad rotation, there is a sense that he is close to handing out all the new caps he is going to before the tournament.
After Saturday's win, there was a name-check for Ulster's utility back Will Addisson who trained with the squad in Melbourne and he may yet enter the equation, but after making James Ryan, Dan Leavy, Andrew Porter, Jacob Stockdale and Jordan Larmour key parts of his match-day 23, it is time now to build experience and grow the team's belief even further.
In time and without the shadow of a World Cup, the magnitude of this season will be fully appreciated but even the way Schmidt picked his teams for this successful jaunt Down Under showed just how much everything is being framed through the prism of Japan.
The experience of being a long way from home for a substantial period of time while playing high-class opposition will stand to the team, as will the latest taste of that winning feeling they are becoming so accustomed to.
They are not bullet-proof by any means, but this Irish team are fiendishly difficult to beat, yet they also have a capacity to make their wins less comfortable than they should be.
Even when they struggled in Brisbane they had enough chances to win the game, but they should never have been defending a one-score lead at the death in Melbourne and might have gotten further ahead in Sydney with a tad more composure and some help from the referee.
The grand finale of a superb series was a tough game to digest given the influence of the officials and the see-saw nature of the play and a tiring Ireland side showed huge character to grind it out in the end.
Their fitness has been supreme all season and their ability to manage players and avoid injury is the envy of their rivals.
Conor Murray, Johnny Sexton, Robbie Henshaw, Jack McGrath, Tadhg Furlong, Peter O'Mahony and CJ Stander were all on last summer's Lions tour, but a year later they were starting and winning a final Test at the end of a long, hard season.
They can happily bask in the glory of it all for the next few weeks - the Leinster contingent may never have a better summer - but when they gather in a Carton House room in August, Schmidt will challenge them to take another step up.
Whether they can do it or not will determine whether the World Cup quarter-final glass ceiling can be broken. If it is, then anything is possible.
What this series showed was that even at the end of such a superb series, Ireland cannot expect to beat members of the Rugby Championship away from Dublin without an immense struggle.
England will bounce back, France are on the up and South Africa are showing signs of life. Argentina and Scotland are enigmatic, but Wales are building again. New Zealand remain a class apart, while even the United States and Japan made some noise in the past month.
After such success it is easy to wonder how Ireland can go even higher in terms of performance, but there is scope to improve.
Once they get through a couple of phases, their attacking game remains somewhat one-dimensional and it becomes difficult to power over the best defences - especially as fatigue sets in.
With Garry Ringrose in the team, Ireland look a far more exciting and inventive prospect but the physical capacities of Bundee Aki and Robbie Henshaw are difficult to ignore. Finding the right balance in midfield will be key.
There will be some concern about how the set-piece creaked against the Wallabies and, with Greg Feek now working remotely from Japan, the scope to improve the scrum might be limited.
And, while he has now found the much sought-after depth in most positions, there is still significant risk to Ireland if they lose Murray or Sexton.
Joey Carbery did well in the series opener, but there was still a noticeable improvement when Sexton came into the fray.
Ireland are praying Carbery will hit the ground running at Munster and stay fit enough to start at least two of the four November Tests.
Despite not coming on in Sydney, Ross Byrne will have gained valuable experience in training while there is strong talk of an as-yet unnamed Irish-qualified No 10 arriving in Ulster to bolster the options. Tyler Bleyendaal is another who could come back into the frame if he can get a run of games.
Still, Sexton is so, so important to the team and if anything happened to him in Japan it would be disastrous.
At least Carbery got some much-needed experience on tour, whereas Kieran Marmion and John Cooney were limited to brief cameos off the bench as Murray continued his run of outstanding performances.
With 15 months remaining, Ireland are in arguably their strongest position and, while there are a number of risks, they are primed for a serious assault on the World Cup.
Before they focus on that, they must reflect and enjoy the fruits of a most successful season.
It won't be forgotten.