I don't think there was any way the war would have ended in 1862. McClellan wasn't the man to end the war, they needed a real fighter to end the war, and in 1862, they didn't have one. They had several people with potential, who needed time to develop their talents.
I'm not much of a McClellan-as-battle-commander fan. I don't see him as the type of commander to drive the Rebels to destruction, but he might not need to be after Richmond falls. Routine military competence by the Union might be able to end the war (or most of it) quickly after Richmond fell.
My point is that a loss of Richmond that early cripples the military-industrial development of "the South", loses them what are arguably the most important cities (and largest) they have, opens up their heartland to invasion, probably loses all chance of foreign assistance, and probably losing most of the resources in Virginia to the Confederate cause.
The Confederate command structure is in bad shape if all this happens. Their political structure would be quaking and trembling. To find as bad a situation in the American Revolution, you'd have to look at December of 1776, when Washington was running across New Jersey for the Delaware River. "These are the times that try men's souls ..." Thomas Paine said. Asked by a friend at this time , in the dark of December, what he would do if the Revolution dissolved, Washington said he would go to the wilderness of Kentucky with whoever would follow him and continue the fight.
The Rebel high command at this time is Jefferson Davis, Joe Johnston, Bragg, and E. Kirby Smith. Robert E. Lee is a staff officer, regarded as a failure by many or as the "King of Spades". Jackson is a hero after the Valley Campaign, but still junior. With everything falling apart, the Confederates would have had no obvious equivalent to George Washington.
Starting at Christmas, 1776, Washington in 10 days created the dazzling victories at Trenton and Princeton. In far-off Prussia, Frederick the Great would comment on the brilliance of that turn-around.
Could Lee become what Washington did? I admire Lee, but I don't think he was capable of being that man, just as I don't think Jefferson Davis was capable of being Abraham Lincoln. With Richmond falling in mid-1862, the Confederacy needed a Washington to survive; even if they had one, things would look very grim.