Not at all.
It could be expected that the settlement of the West would take a little slower since there won't be the manpower for the US Army to draw upon. There wouldn't be the same scope of industrialization in the North and there most likely wouldn't be any major federally funded projects. With the likes of Virginia, North Carolina, Tennessee, and Arkansas remaining in the Union they would still at as some sort of brake, as the South historically did, in counteracting the growth of the central government.
Politically, the idea of secession wouldn't be settle since Virginia, North Carolina, Tennessee, and Arkansas would still be advocates. Its possible that the original concept of the Constitution, in regards to the even balance of power between the government and the states.
Actually, I think the west gets settled a lot faster due to three factors:
1. If the war is settled in short order (say 1862) there's far fewer casualties amongst the young men of the period. They don't die, they go home have kids, population expands.
2. Immigration. People were coming over in droves during before the war, they came over in droves during the war, they came over in droves after the war.
3. All those people have to live somewhere and the west has plenty of land, plus the Homestead Act to make it more easy to acquire.
The settlements have to be protected, so the army, after a brief period of demobilization, enlarges accordingly to facilitate settlement. They're going to be out there anyway to protect the trans-continental railroad construction and settlement will probably be heavy along the trans-con route, so figure the army will get as large as it has to to protect westward expansion.