Yoda had a vision that the galaxy will be free of the Sith, yet neither he nor Obi-Wan believed redeeming Anakin to be possible. Not seeming to be ones who would leave everything to fate, it's more probable they formulated a plan to defeat the Sith or at least liberate the galaxy. They chose to only train Luke and keep Leia hidden so as not to bet all their chips on a single all-or-nothing showdown. Even to the end, Obi-Wan in his ghost form - which one would expect to be wiser and more perceptive of the Force than while alive - continued to insist against attempting redemption and to continue preparing to face Palpatine.
Did the two Jedi Masters really intend a rematch by a newly trained Skywalker against his father and the Emperor combined - who both had experience killing many of the best Jedi swordsmen of the day - to be the finale of their plan, or were they actually planning something else? In the event that a battle was really what they were planning for, then did they send Luke off Dagobah in RotJ genuinely believing he stands a chance to win the impending battle against both Sith Lords, or did they, rather uncharacteristically in my opinion, gave up trying any further to train him, resigned instead to leaving Luke's success to fate, thus getting ready to move on to Leia if he indeed failed as they seemed to have expected?