Don't be silly, they're not lifepaths, they're prologues, after those prologues everyone ends up in one path, as a streetkid.
Semantics. You roleplay whoever you want after prologue and V despite initial backlash for being "streetkid" is actually much more neutral because the slang he uses and type of speech is actually pretty common everywhere from corpos to nomads.
Again, it's impossible to be certain about any of this, but if you look at the weight and tendency of the promotional material up to 2018, the game was meant to be different. Certainly some elements of the story would have been in there from the beginning, but not with Johnny Silverhand playing such a central role, especially considering that he's shown in 2018 as having died in 2076 in one of the promo videos, and considering that screenshot showing him as merely an inspirational figure. Neither of those can be excused as "fluff text" since they're ABSOLUTELY CONTRADICTORY to Johnny Silverhand having the important role in the story he has now.
For example, there's the ending, which obviously has 3 "flavours" (Nomad-ish, Street-kiddish and Corpo-ish), then there's the underdeveloped theme of the AIs and the Blackwall, really only shown in the Voodoo Boys/Netwatch questline, and jammed rather awkwardly into both the Nomad-ish and Street-kiddish endings, but not at all utilized in the corporate-ish ending. But notice how, in one of the promotional vids, Pacifica is shown as a place unto itself with its own particular flavour, not just as a backdrop to one quest in the game and a few side-gigs (as it is now), and how Netwatch figures more prominently in one of the other promo vids. That underdeveloped theme is also hinted at in the Peralez quest - which really looks like it ties into the whole AI thing. There's also the hint that Delamain's schizoid problem is some sort of AI virus.
I think the original intention was for the story to be more general and related to a) Arasaka's pursuit of immortality (so the biochip definitely figured in there), b) the AI/Voodoo Boys/Netwatch theme, and c) probably something related to the Nomads and the theme of ex-military Cyberpsychosis, which is heavily peppered throughout the game (perhaps re. the question of whether cyber-enhancement is worth it or not); the first being more related to the Streetkid V, the second more to the Corpo V, and the third more to the Nomad V.
It's kind of pointless arguing about it. But I do think everyone should look at that video, to remind themselves of exactly what the promotional videos were saying, and how that differs from what we've got.