I have to disagree with the assertion that in a CSA victory scenario, the USA will begin to orbit the UK. Yes, at least for a time, the USA will be weaker vis-a-vis the UK and have less economic leverage. Having said that, the "rump" USA, as realistically seen geographically, with its resources, population in 1865, and the immigrants that will come to the USA (including some that would have gone to the CSA but will be less attracted to a slaveocracy) , will still become an industrial and economic powerhouse not much later, if at all, than OTL.
Given that any CSA victory scenario will probably mean more support by the UK of the CSA, either without actual participation or the RN escorting blockade runners, or even direct combat operations, the USA will NOT have a warm fuzzy feeling for the UK. Furthermore the CSA will most definitely be in the UK orbit, and I would expect the UK to mount a successful drive to replace industrial imports the CSA was getting from the USA with British products. That won't endear the UK to the USA either.
While the scenario of the CSA a formal UK ally and the USA a formal German ally is unlikely (though not impossible/ASB) I can certainly see a wide gap between the USA and UK lasting for a long time after the ACW ends with the CSA in existence.