Hey, GTA VI is taking longer and with a multi-million dollar company behind it, just saying 😁
And don't think of the version number as a sign of (im)maturity: it's just the versioning scheme 99% of the AVN developers use. Instead, you should consider every "version" a fully developed chapter/episode (e.g. 0.1 = ch/ep 1, 0.2 = ch/ep 2, etc) and not as an alpha version of the complete game.
As for how many chapters there will be, I'll leave that for Panda to answer.