If Reynolds did take command, then the entire Pennsylvania Campaign will be altered. Reynolds was offered command prior to Hooker's relief and was anxious to get at the rebs, especially after Pennsylvania was invaded. Supposing that he was suddenly in command like Meade, he probably would have been more aggressive in his approach relative to Meade's rapid and prudent movement towards Gettysburg. Given his more aggressive mindset, there would probably be no Pipe Creek Line or Pipe Creek Circular. The Army of the Potomac may even concentrate at Gettysburg earlier on July 1. However, I am not as high as others on Reynolds. Reynolds, in spite of his stellar performances as a brigade and division commander, really did not perform well as corps commander. He considerably limited any benefits that might have been gained by Meade's breakthrough: The corps commander could not be found. Reynolds was on the Federal artillery line, personally ordering batteries where to fire, how to elevate, and according to some accounts, at times was off his horse sighting guns himself. None of Meade's messengers carrying Meade's pleas for reinforcements found him. Reynolds was not really engaged at either Antietam and Chancellorsville, and his last battle, Gettysburg, saw him acting at a battalion commander at best. This sort of micromanaging is pretty similar to A.S. Johnston at Shiloh, where he met his end.
The left wing would be under a new commander, possibly Sickles or Howard.
The left wing would have been under Sickles if no changes to the left wing's composition were made. Sickles had superiority over Howard and Doubleday (Reynolds' replacement). However, there were plenty of officers who were Sickles' superior such as Sedgwick, Slocum and Meade. This would, however, involve changing the left wing's corps.
