Potential spoilers ahead for past games: I think it's great that Bethesda tries to keep the role-playing open for the player so they can be good or evil, but I don't think they should have to do it 100% so that there's a full-good story arc and a full-evil story arc, or one that's neutral even. If there was always an evil ending, those who finish the evil ending and aren't the savior but rather the devil would expect all lore to also include this alternative, and that's extremely messy. Bethesda doesn't owe the players that, you couldn't join the big bad dragons as the Dovahkiin in Skyrim, you couldn't join the Enclave in Fallout 3, you couldn't join the Daeda and the Daedric Prince of Destruction and betray Martin in Oblivion, and so on. Don't be under the illusion that Fallout 4 will be any different, they still have a story they want to tell.

Well, I do not know you could be really evil in Fallout 3 and NV, just imagine dumping the modified FEV in the basin or destroying Megaton, or joining the legion in NV with all what it entailed. In the end you still will be able to a lot of awful things as the trophies do not cover many sidequests.

Yes you can join the railroad, but obviously it is not necessary to finish the main quest. And even if you choose not to join you might not be hindered in other quests to do as you please with androids. Also the factions themselve might have hidden agendas that are more than just black or white.

I wonder though if you can join more than one faction. As for bad things I can at least see that you can indeed make the Prydwen go down, which might be quite an evil act to do. So all in all I would not be too fast to assume you can not be really evil, just by judging from some achievements.

Awful lot of presumptions floating around.

rumour speculations and hearsay as so many things we ve heared on this forum the last 4 months

we will know what it is all about in less than 14 days

It's an added bonus, though not necessarily a checklist requirement to have all franchise lore reflect evil decisions. New Vegas did just fine having different endings reflecting your in-game decisions.

Sure you can't join the dragons as Dovahkin in Skyrim, but why not join the dragon priests or betray Martin and have an ending where you stop Akatosh's destiny? I'm pretty sure a few Oblivion players grew tired of being Martin's errand [censored] boy. Sure an evil ending doesn't have to be canon, though it could be just as rewarding. Even Miraak from Dragonborn may have been halfway there to becoming a dragon priest himself due to his selfish agenda.

My point is, in the end, karma doesn't really matter too much in Fallout games since you are tagged as the protagonist, no matter what you do.

Speaking of which, I hope you don't get negative karma for dumb [censored] like stealing or lockpicking even with no witnesses around.

What you say is definitely a possibility. Hopefully there are much more evil deeds you can perform this time around with a satisfying payoff. Good question about joining more than one faction. I assume you can initially start quests for all factions, though eventually certain faction quests you complete would instantly gain you a bad reputation with an opposing faction. At least, that's how I hope it would play out. Then again, it might be similar to Skyrim, where you can become the top dog in all factions.

Lol

The OP's first 3 spoilers might be right-

...But where did these "facts" come from?

I approve, the recent achievemnt leak didn't prove this

Fallout games always have some form of direction or goal;
1 - find a water chip
2 - find a geck
3 - complete project purity
NV - settle who owns vegas

Its how you went about enacting that was the whole "karmic choice" of it all..
Do you abide fully to laws and save people or do you run through like a phsycotic [censored] and kill everyone?

I take everything posted not only this topic but any other topics grain of salt intill the game is out or official words from Bethy or proof.

Yes,also nothing is stated about settlements

Only:

Ally with 3...