The North gets a considerable number of additional soldiers, several talented commanders, and the logistical and economic strength of Virginia in general. The South loses those things. To the North, it's a nice bonus. To the South, it's a devestating blow that cannot be overcome. Without Virginia, the South will be extremely short on troops, supplies, weapons etc. etc.
The legislatures and the people of North Carolina, Tennessee and Arkansas are no doubt aware of this. They will follow Virginia's lead, and stay in the Union. And on the off chance that they don't, considerable segments of the population will support the North, and those states will be quickly overrun by the Union.
Since the frontline is now much further away from Washington, the South has a snowball's chance in hell when it comes to an offensive strategy, so all they can really do is entrench and try to hold out. Considering their lack of men and supplies, that strategy won't work. At all. On the other hand, Lee will be commanding the Union armies. We must remember he was called "granny Lee" at the start of the war IOTL. One may expect his initial approach to be cautious, so the war may not be over as quickly as it could be.
Nevertheless, the Confederacy has until early 1863 at the very best. It'll be clear that they are going to lose much, much sooner. Considering Lincoln's viewpoints on the matter, there may still be an emancipation proclamation, but only if the war drags out long enough. The shorter it is, the less likely a proclamation will be. And even if it is issued, Lincoln will probably use it as a tool to manipulate the South into submitting: states that surrender at once will be exempt. And I expect that by that point, the South will surrender and keep their slaves, rather than fight on and certainly lose them.
Even if radical Republicans push for complete abolition after the war, there will be more slave-holding states in the Union (even considering that the former Confederacy will likely be under military rule for some time), and it is unlikely that abolition will pass. Especially if keeping slavery was the primary condition of the South's surrender.
All in all, a world where the Confederacy is smaller and the war is shorter may not be a better, brighter place. Not if you happen to be slave.