I'm not so sure that the Nazi Germany - Russia analogy is correct in this case. While Featherstone's CSA is a direct parallel, the USA is in no way similar to the USSR. For this, and a few other reasons, I would speculate that a rerun of the 41-45 Eastern Front is unlikely.
The USA is a fractured society with a divisive Labour - Capital struggle - more like France 1940. Its political leadership has been weak even to the extent of caving in to some of the CSA's demand. Even after a surprise attack by the CSA, I can't see the Democrats wholeheartedly supporting the Socialists. Again, I see a parallel with 'defeatist' parties in France.
It is too easy to assume that because OTL America was an industrial powerhouse, the USA here will be the same. It may have the potential but remember here the Depression was not moderated by 'New Deal' politics. Also, the USA hasn't had the two years of 1939-41 to begin an increase in military related industry. Also, in OTL, the USA was an invulnerable base area. Attacks on its own territory may degrade capacity significantly. Also, unlike OTL is doesn't have the resources of the areas now ruled by the CSA.
That leads me to the next big difference. Oil. As far as I can tell almost all the oil produced in North America at that time was in Texas-Oklahoma (Sequoyah). This is either now (or assumed soon to be) in CSA hands. As an aside President Smith should be impeached for letting Houston go. The other major oil sources in the world are a) overseas or b) in unfriendly hands or both. The USA's overseas trade is vulnerable to CSA, Japanese and British intereference.
On the military front, the USA is woefully under prepared. As remarked by both Morrel and Dowling it is preparing to refight the last war. Even Morrel's new tanks (barrels) are a state of the art design from the 1920s. I certainly doubt that they have evolved a useful doctrine for them. Gas may be an impediment but I suspect as in our WW2, it is unlikely to be used. Again, Morrel and Dowling's distaste of it is made obvious and I feel they reflect a majority opinion. Quite aside from which gas is only useful against an unprepared enemy, preferably one that can't retaliate. Also, in a defensive war, the gas will have a serious negative impact on the local civilian population. Killing ones own civilians is not generally considered a good thing.
The other problem with the USA is its obsession with a large navy - understandable after the wars (WW1 and the Pacific War). Unfortunately it is a battleship navy at a time when these monsters are about to be consigned to oblivion. Its bases are vulnerable to blockade and it has a major liability in Bermuda. (Anyone care to guess this is going to be the Malta of these books?)
The Home Front - as I have said, the USA is divided on class lines. The CSA is much more united and will remain so, as long as it keeps winning. Even then, major unrest is not certain. Most opponents are either dead or in work camps. The USA also has the problems of Canada and Utah. One needing to be occupied, the other a major potential headache.
One other "problem" is that the USA is a democracy. Democracies react badly to losing - even Churchill was nearly voted out of office in 1942. President Smith appears to be no Churchill. I can't see him rallying people after a few disasters.
The main thing the USA has is space. Unfortunately that may not be enough. The main industrial areas of the mid west are (especially with the border now on the Ohio river) within striking range of CSA armies and air forces. Louisville-Chicago is approximately 250 miles as the bomber flies. Whether or not the CSA has a strategic bombing capacity is not clear from what has been in the books so far. I am also assuming that as with everything else the CSA will have an advantage in the air.
So, anyone for a blitzkrieg followed by a "Vichy" USA ?