Some ideas regarding the US...
- Confederate, British and French culture became viewed has generally taboo, unpatriotic and even potentially treasonous. With the cultural vacuum being eventually being filled by German and Austro-hungarian culture. Think instead of books and movies about charlamange and Teutonic Knights instead of King Arthur in the US.
- Post Second Great War the crumbling Austro-hungary started encouraging immigration of the more troublesome nationalities within the Empire to the United States. Specifically into former Confederate territory with the US considering them more trustworthy than the "Rebs" and generally being considered collaborators by Southerners. This would eventually lead to some rather nasty ethnic conflicts in the 90's, when the US suffered a nasty break up similar to the USSR and Yugoslavia.
- "Yank" English slowly starts diverging heavily from traditional American English with the introduction of various German loan words.