While the departure of Stuart Lancaster to Racing 92 has not been confirmed, the likelihood is that Leinster will be without their most important signing since Joe Schmidt from next summer onwards.
Gerry Thornley has reported in the Irish Times that Lancaster is due to have a video meeting this week with Racing's head coach, Laurent Travers, and club president, Jack Lorenzetti, and that the move could be finalised by the end of this week.
No concrete names have cropped up just yet in the rumour mill, as potential replacements, but there are plenty of possible roads for Leinster to go down, particularly in a busy World Cup year.
McNamara is the brightest Irish coaching prospect in the game, and has held the position of backs/attack with the Sharks since last summer.
His previous jobs include being the head coach of some of the most exciting Ireland U20s side's the country has seen, and he also oversaw the ridiculous line of young talent coming through at Leinster while he was Academy Manager. As such, he is already in tune with the Leinster system.
Stuart Lancaster was Head of Elite Player Development at the RFU, prior to taking up the role as head coach of England, while McNamara was previously involved with the IRFU's elite player pathway team.
They are two men with similar backgrounds, and experience in a variety of areas of coaching. Leinster and the IRFU will be keen to see McNamara back on Irish shores, and there is a strong argument that he is the most like-for-like replacement of the men mentioned in this article.
This would be a major coup for Leinster, and could drive them onto heights they are yet to reach.
However, would Ronan O'Gara be willing to work in tandem, and technically underneath, Leo Cullen, for the greatest rivals of his beloved Munster? Would he want to leave lucrative job in sunny France, where he is adored by their passionate fans?
There is also the possibility of O'Gara being hired as head coach of one of England, France, or even Ireland, after the World Cup.
But, O'Gara has stated in the past his desire to coach Ireland, and working at Leinster would provide the perfect pathway to that role, and allow him the chance to work with many of Ireland's internationals.
Sexton has previously expressed his interest in coaching when his playing days are up. He is due to retire after the World Cup, although Leo Cullen recently implied there is hope that he will continue playing.
Sexton is a natural leader, one of the most respected Leinster players of all-time, and knows the team and its attack as well as anybody.
We have seen the likes of Sean O'Brien appointed by Leinster, fresh from retirement, while John Muldoon was hired by Pat Lam at Bristol after hanging up his boots at Connacht.
It would be a sensational appointment, were it to come to fruition.
Promotion From Within
This ties in with the paragraph above (Sexton had to get his own section), as Sexton would not have the experience to slot into Stuart Lancaster's current role.
Andrew Goodman and Robin McBryde both have years more experience and could be suited to taking on a role with more responsibility, while a replacement for one of them is hired.
Leinster may not directly replace Lancaster either. A restructure could be implemented with the outgoing coach's duties divvied out between the rest of the management, and perhaps a new role created.
Super Rugby Replacement
Down Under has always been a breeding ground for future Northern Hemisphere coaches, with teams eager to avail of Super Rugby knowledge and style.
Leinster, given its size, success, and conveyor belt of talented youth, is a massive draw for Super Rugby coaches. You need look no further than Andrew Goodman, who left his job as assistant coach to the best club team in the world.
Potential suitors may include Leon MacDonald, who is head coach of the Blues, or Jason Holland, head coach at the Hurricanes, and an ex-Munster player who spent nearly a decade in the country and was capped by Ireland A.