All true, however I would quibble on the plebiscite issue. The Confederates would, by dint of their historic claims and most likely the arrogance of their representatives, demand the states of Maryland, Missouri, and Kentucky. The Union of course would laugh off Maryland and Missouri (seriously, Stirling Price's campaigns are almost laughable in their repeated failures), but there are scenarios where they might hold bits of Kentucky and cling tenuously to it and demand a plebiscite there. I can see them giving up the counties bordering the District of Columbia, all claims to West Virginia, and all claims to Missouri and Maryland in order to get it. The Union would probably win such a plebiscite so I see no huge obstacle in them granting one in exchange for diplomatic renunciation of other Union territory.
The only other one up in the air is the Indian Territory, the Confederates signed various treaties with the tribes there, and it was such a backwater campaign wise that they could see a see-saw there which might allow for favorable conditions for the Confederacy to request it as a territory. The Union might give it up in such a case.