I really hope for a direct sequel for our V and RO. It makes the most sense to me since we the players are V, We established him/her. That's how we see our self in the world, it's an extension of us, and V is also a great protagonist, badass but also not perfect. to make another protagonist for us to establish and to relate to again would be really difficult imo. And the characters are too damn incredible for just a one-off story, that would just be a sin if CDPR did that, and with the other awesome story arcs, like another corporate war on the verge of happening or the AI beyond the Blackwall with Alt preparing for war. Would love to see and experience those as V (us, the players) and not some random new person that has no connection to them since V is the one who has been talking to different corporations as well as Atl and is the only person I know of to have gone beyond the Blackwall and comeback. And have our RO and other characters there, to see how they would handle/help these situations. As for adapting the endings, they could do that in the expressions with the three endings where V is still alive. Have them converge to a focal point, like no matter which of the three endings you chose (where V is still alive) the cure for him/her is here in this location, and you have to do x, y, and z in order to get it, with some added flavor depending on which ending you had, like different missions and dialogue, just as a quick example. The other endings, V is dead or Johnny has V's body and V is gone into cyberspace forever (as Alt said), so then those stories would end there, because of player choice or the player didn't work hard enough in the game to get the other endings (as Pawel said in one of his streams).
As a side note, I still find it interesting that there are three life paths and three endings in the game where V is still alive. It might be nothing, and probably is, but I just cant shake it.