As he took his leave of Leinster, having successfully replenished the trophy cabinet with three trophies in the space of eight days, coach Joe Schmidt reflected wryly on a question he was asked in the early days of his time in charge of the Dublin side.

It was put to him in September 2010, in the immediate aftermath of Leinster's 29-13 defeat by Treviso in the Stadio Monigo. Leinster had also lost to Glasgow two weeks earlier and the alarm bells were being rung by the Irish press. "Joe," asked one breathless reporter, "is this the beginning of the end for Leinster rugby?"

As Schmidt would deliver the Heineken Cup to Dublin just eight months later, and then do it again the following year, he would have been justified in treating the question with some scorn. But then, in fairness to the fellow who asked it, Leinster had been threatening to peg out as a competitive force for years. Their obituary had been polished many times already before they went down in Italy.

The doomsayers' logic was – and sometimes still is – that the years were taking their toll on the great generation of Leinster players who emerged around the turn of the millennium. Yet as each star of the side has waned, another has emerged, and the Leinster bandwagon has rolled on. So while Schmidt, Jonny Sexton and Isa Nacewa bade their farewells to Leinster after the RaboDirect PRO12 grand final on Saturday, it would be a rash pundit who predicts that the end is finally nigh.

Only an Irishman could get away with describing someone as "fairly irreplaceable" but when Brian O'Driscoll applied that tag to Sexton after this game we kind of knew what he meant. The more-than-fairly irreplaceable O'Driscoll has been the golden thread that has linked a succession of great Leinster sides together, and as he prepared to set off on his fourth Lions tour – an achievement unmatched in the professional era – the great man gave an insight into the culture of his club.

"Jonny has been instrumental in our success," said the 34-year-old centre. "He will be a big loss for us, but the show goes on. That's what happens in rugby. Guys come and go.

"It's a standards thing for us. We demand a certain amount from ourselves. We're in a good place, but we've got to continue driving on. We can't remain stagnant, we've got to continue winning."

In which regard, the British & Irish Cup won by Leinster's second-string in Newcastle a week past Friday may prove to be more significant, in the long term, than the Amlin Cup and PRO12 titles they have also hoovered up this month. The departures of Schmidt, Sexton and Nacewa lent an emotional aspect to this marvellously atmospheric occasion in Dublin on Saturday, but nobody was in any rush to bill it as the beginning of the end.

Schmidt, though, offered intriguing insight into how he thinks next season's PRO12 season could pan out. Asked for his thoughts, the New Zealander's smiling prediction that Leinster, Munster, Ulster and Connacht would fill the four semi-final slots next year may not have been unconnected to his new role as Ireland coach, but he did have more serious things to say about the tight nature of a competition whose clubs have provided the majority of Lions tourists this year.

"Scarlets gave us a couple of lessons," said Schmidt. "I can't see Munster being out of the top four too many times. Ospreys are tough to beat when they have their full complement of players, and I think Treviso are a dark horse and they have some super players.

"Glasgow were incredibly tough here in the semis. I got a text from Gregor Townsend to say 'good luck' and I think he has done a super job. They have some massive talent and we were probably lucky to sneak through to this final."

In many ways, Leinster's success against Ulster on Saturday mirrored their 17-15 win against Townsend's Warriors at the semi-final stage two weeks earlier. Shane Jennings claimed a try from a driven lineout that had the same combination of precision and ferocity as the one that led to Jamie Heaslip's score against Glasgow, while Sexton's try-saving tackle on Ulster's Robbie Diack was remarkably similar to the one which had denied Ryan Grant a score.

As always, though, it was craft and experience in contact which gave Leinster their most important advantage, as Ulster's Rory Best ruefully reflected. "As always, we get 10 out of 10 for effort and we really competed for long periods of the game," said Best, who will join the Lions squad after Dylan Hartley was banned for 11 weeks for verbally abusing referee Wayne Barnes in the Aviva Premiership final. "But it came down to the breakdown and they were a lot more street-wise than we were.

"They are very good at slowing ball down and getting away with it. You have to give them credit. We were maybe a bit naive there. We were not as ruthless as we should have been."

Best did make the fair point that Ulster got far closer to Leinster than they had when losing to the same side in last year's Heineken Cup, and predicted that they will be back in the mix again next season. Others will feel the same about their prospects. This has been a superb PRO12 campaign; already, the pulse quickens at the thought that the next one could be even better.