So yeah, there's certainly possibilities, but the main problem is finding how all the possible situations could happen plausibly in a single TL.
I think it might be accomplished through a different (yet recognizable) situation at the end of WWII (especially in respect to what is done in Central Europe), and much messier decolonization caused by full Western commitment to self-determination. Or something!
Most of those (except maybe Scotland depending on the POD) are extremely unlikely to happen with a POD past 1900 without a Nuclear war...
I'm going to have to agree with this. I edited a clarification into the OP to address it. Although this isn't to say that culturally distinct regions in largely stable, industrialized Western countries couldn't secede (Scotland and Quebec are perfect examples), it's unlikely.
Other options would have been additional states in Europe, for example a post WW2 breakup of Germany into its pre-confederation/empire collection of states. I believe spain and Italy could also have similar subdivision occuring.
A bloodier end to WWII might bring about stronger anti-German and anti-Italian feelings, prompting the Allies to dissolve the two countries into numerous smaller, unthreatening states. (Although they'd make a poor bulwark against Soviet communism -- the reason this choice was avoided in OTL, IIRC.)
As for Spain... a different end to the Spanish Civil War? A premature death of Franco (coup? assassination? chokes to death on some paella?) prompting a second civil war?
Oh, OK. Disregard my maps then, although they can be used as references.
If WWII does come about, presumably the aftermath could include:
- Morgenthau Plan divides Germany into HRE-style mini-states
- Due to some kind of serious international animosity, Austria is broken into four separate countries each backed by an Allied occupier
- Japan is divided into Soviet, American and Chinese occupation zones and later breaks apart along those lines
- Roosevelt's plan to invade Spain is carried out; Catalonia, Galicia and the Basque Country declare independence
- A Korean War analogue results in the nuking of Beijing and the fracturing of China into another Warring States situation
No worries -- they're beautiful maps and I'm happy you shared them!
- See my answer to one of the above quotes.

- I think having East and West Austria would be pushing it, to be honest -- the reason Austria didn't suffer the same fate as Germany after WWII (division and occupation) was because the Soviet's zone was too small to be economically sustainable, and the Allies were loathe to let Germany keep Austrian territory for obvious reasons. Maybe the Soviets bite the bullet and Moscow fully subsidizes Vienna-based East Austria anyway?
- See my other answer about Spain, but I like that too -- it's creative and I could see it happening in a world where Italy and Germany are also dissolved.
- Again, something I could see happening. What if no one wins in China and the conflict continues indefinitely, with both sides pouring in weapons and money?
On China: could linguistically distinct states in Eastern and Southern Coastal China be carved away from an ethnic Han, Mandarin-speaking state based along the Yellow River Valley? I think a Cantonese nation state in Guangdong might be possible, either as its own entity, as the realm of a warlord, or as the haven of the KMT.