John Fredrick Parker
Donor
The Tidewater might have adjustments, but the more industrial west could benefit from labor costs; do agree that slave prices will fall, which in addition to meaning higher profits for planters in slave states that have significantly less inclination to follow Virginia's lead, will also mean that those that may have such inclinations (Maryland, Missouri, etc) will have an easier time of manumission.On the other hand, there's a chance some remaining slave states could laugh all the way to the bank, with slave-based agriculture pulling bigger margins as Virginia owners start a fire sale and costs of production rise in Virginia.
So on the whole, this means massive short term windfalls for slave powers, followed by a steeper decline in their political power... which makes sense, since generally speaking you need one to make the other happen without substantial violence.