Assuming you don't choose the suicide ending, it's unclear if V lives or dies because at least the Star and Sun ending imply more work that's going on. Sun you're on mission to the Crystal Palace and Star you're hunting contacts. I don't remember if anything is implied in the Temperance ending, but Johnny gets on a bus and presumably leaves Night City? I don't think they do the endings the way they do without there being more context, like i,e expansions. Yes, V gets 6 months to live from Alt, but look what V manages to accomplish in a few weeks. I don't think it's out of the realm of possibility to find a miracle cure in 6 months. There's part of me that wants a straight up answer, but I also wouldn't mind it if they did leave to player interpretation. I guess it all depends on what they want to do with V for presumably sequels.