What the ????
Lincoln had issued the Emancipation Proclamation at the beginning of 1863, which de jure freed about 3/4 of the slaves. There would be no going back from that.
And Lincoln tried other methods to end slavery during the war.
By mid-1863, the great majority of Northern men had decided that whether slavery should be abolished for moral reasons, it was a perpetual danger to the Union and must be abolished for that reason.
I cannot see any evidence that after an earlier victory, Lincoln would not pursue a program of complete and final abolition. It might be gradual and would take some years, but he would be on board with any program that did not threaten disruption of the Union.