A double Grand Slam winner with Wales in 2005 and 2008, Henson has given "unconditional leave" by the Ospreys to try to overcome his on-going injury worries, but has not been involved with team training or any of his side's matches to date this season.
Wales and Lions coach Warren Gatland has already said it would be a huge loss for the national side if the 27-year-old Henson were to quit with so much time left to achieve so much more than he already has done in his career.
As well as those two championship clean sweeps with Wales, Henson also helped the Ospreys to win two Magners League crowns and the EDF Cup. In his younger days he was named as the IRB Young Player of the Year.
The Heineken Cup registration deadline was last Thursday and Ospreys director of coaching Scott Johnson omitted Henson in favour of a number of younger, untried players.
That doesn't stop Johnson from adding Henson to his squad as an extra player should the Ospreys reach the quarter-finals stages again this season, or draft him in as a direct replacement for an injured player during the Pool stages.
But in all likelihood the 2005 Test Lion centre will not be facing English champions Leicester Tigers or French giants ASM Clermont Auvergne.