One caveat to think about, normally in these issues, players are not in the middle of their playing careers. Most player issues, academic or otherwise, are brought to light before they play games. The regaining of eligibility is usually dependent on some "correcting of the wrong", ie paying money back and such.The correcting of the wrong has either taken place, or a plan is set forth for doing this before the player actually regains his/her eligibility. So long story short, if this happened during the season, they would regain eligibility upon completion of "correcting the wrong", which is something they cannot proactively do.
John Wall had issues due to some monetary benefit (as others have), and his regaining of his eligibility was contingent on sitting out 2 games and repaying the monetary value. Repaying the value corrected the wrong, and sitting out was the punishment. He corrected the wrong before he played games, and then did his "time". Without repaying the value, he is sitting longer than 2 games. In fact, he is probably sitting until he repays it, or has a plan to do so (as was the case with the Kansas guard).
So for the UL players, correcting the wrong today would allow them to become eligible (though most would be ineligible now for other reasons) now, but would not make them retroactively eligible.