My thoughts are Halleck would have resumed command again for starters. At first Lincoln and Grant did not want Sherman to cut his life line and take off for Savannah. But after harassing Grant and circumstances chaging it looked feasible to Grant and Grant gave the go. Remember how Halleck held Grant back going to Corinth? Sherman's March to the Sea would have been too wreckless for Halleck and he had Lincoln agreeing with him.

This case being so we have Sherman sitting at Franklin or even Spring Hill instead of Thomas, Scholfield, Stanley and Wilson.

Also I don't believe Sheridan would have got the orders to cut loose on the Shenandoah Valley.

Although history tells us that Sherman would have been the best choice, we have to take in the political nonsense both Armies were experiencing at the time, for instance Thomas would not be Shermans scapegoat at Chickamauga thus was sent to be a subordinate to Schofield in Tennessee.

Sherman was not a politician and the fair haired child of the Union. He was Grant's fairhaired child only.

By taking all this in, my personal point of veiw would be that the Confederacy would have survived the War at least another year more than it did. With events like they were,,,,Lincoln assinated 9 months later, who knows I could be living in the CSA right now. and No I don't believe that would be a good thing.