All Might will disclose the truth about his injury after the Deika City operation.
There is a good chance that Re-Destro will prove himself a formidable foe against even a healthy Symbol of Peace. Should the worst happen, and All Might end up getting to his one-hour limit by the time of the fight, it would make sense for him to reveal it to the Top 10 and let them be prepared for his retirement.If the above happens, Endeavor will get his Heel Realization after it.
Once he finds that the title of Number One Hero will be handed over to him much like in the original timeline, Endeavor will enter his atonement arc. Maybe he would leave his children and bring his wife to live with them, to show he really means to make amends.