1) Vehicles
Pass. The only really feasible option here (since all the roads are basically destroyed and none of the cars that are just around are actually built for offroading so much as they are for family cruise nights to the drive) is a hoppy-boppy buggy thing that could navigate the terrain and I see a) no reason for that to exist and be lying around b) no fuel sources to legitimately power it c) no way that ownership of such a thing - were we ignoring a and b - would not attract every raider, bandit, society trying to build itself, caravan owner etc. etc. etc. to wanting to kill you and take it from you for their own use. Also - I don't want a Mad Max vibe OR a Borderlands vibe in my Fallout fantasy.
2) Improved combat and gunplay
Yes. Provided we don't take it to the point of making into a true FPS with cover and all the nonsense that just gets in the way of the wandering the wastes mystique.
3) Epic Moments Epic
Sure - probably folds a bit into point 2, but again - set pieces can detract from the idea of it being "our" story of "our" wastelander / vault dweller, so a steady hand for a big finale - okay; a continuous line of events? less so.
4) Less Bugs
Obviously.
5) A Livelier World
You do realize it's a wasteland right? That these are the survivors of a catastrophic event that depopulated the world? Just checking. More "random" encounters out and about would be nice - but I don't really think seeing a lot more people about and more settlements and - dare I say? - communities will really lend itself to that whole "post apocalyptic" thing we're trying to have.
6) Improved Karma System
I think some more accuracy and fine tuning to the existing karma system could be beneficial. I will say though that just because you make one, albeit really large, mistake of epic proportions (say, nuking Megaton as per your example) that you shouldn't be able to work back from it on your own journey. In fact, I could argue that someone who comes out of the vault, nukes the town to get ahead and fancy perks, realizes what they've done, and then spends the game trying to make up for their mistake is having a rich and personally motivated gameplay experience that only open world games like Fallout have the potential to deliver on. Nothing should be wholly irreversible in making your character who they are - let the journey be the judge.
7) Mor Obsidian like characters
Eh, I don't have a problem with the characters, but obviously there's always room for improvement in writing them
8) Even More Hardcore Mode
ONLY if it's wholly optional. I played Hardcore mode for NV and I liked it - it could have been harder for my tastes too, to be honest - but not everyone's into that and I'm not even into that *every* time I play the game. Sometimes you just want to enjoy the atmosphere of the game and cruise, and that should continue to be available and welcomed by the devs and other players. I for certain don't want Fallout to be setting any "Dark Souls" hardcore or gtfo standards in our community - we've plenty too much of that already.