The Leicester, England and Lions scrum-half has decided to call it a day while still at the top of his game.
The Ireland international has denied he has signed a new deal at Munster but a move to Leicester now looks off the table.
England captain Maro Itoje will return to captain a Saracens side containing four of his international team-mates during the Guinness Six Nations when they host Harlequins in the Gallagher Premiership on Saturday.
Racing 92 emerged as surprise contenders for the signature of former Australia and Argentina boss Michael Cheika, who is leaving Leicester Tigers when his contract runs out at the end of the season.
Leicester Tigers centre Dan Kelly has signed for Munster ahead of next season, as reported by RugbyPass.
Leicester Tigers have sounded out former England captain Owen Farrell about making a sensational return to the Gallagher Premiership less than a year after he moved to Paris to start a new chapter of his career with Racing 92.
The 29-year-old Byrne has slipped down the pecking order with Leo Cullen’s runaway United Rugby Championship leaders, this season coming off the bench five times in the six games that he has played since the start of the campaign.