Well, it won’t really be a prologue any more – it’ll be half the game, two chapters instead of one. It’ll now have the start of the Erjan, Jev, and M’kyar romances, expanding on Sojourn. It’ll now also (I think) have the introduction of Erjan’s sister Dilek, who can accompany you to Irduin, tying the book together a bit more.
And Irduin may get a little bit of Xaos in its ending.
Oh, I’m sorry. 
As @WinterHawk noted while I was writing this post, going this route may well lose me a bet with a friend by pushing the overall series length to six books. And I recognize the risk that this is the first step* in XoR bloating Jordan-style to a twelve-book series that CoG has to ask Paul Wang to finish because I die first. But I’m going to keep fighting that outcome.
*well, second or third – my original proposal to CoG was for two games
I did ask myself that. But since we first talked about it on the forum, I’ve come to think that attacking the Wardgate would be a major strategic mistake, and Herne knows it. And I don’t want to move up the purging of Sojourn, because of my plans for a Grand Shayard plot where you intercept a military dispatch and have the option to affect the number of Phalangites and Theurges sent against (a) Sojourn, (b) the Rim Commotion, and (c) the Cabelites, with clear implications for how many remain in (d) about-to-be-highly-vulnerable-to-your-attack Grand Shayard. (Spoiler protection for responses to this, pls.)
So while there will be some expansion of Ch 1 into a new Ch 1-2, I don’t think it will involve dusting off those ideas from earlier.
I think so, too. It’s the MC’s immersion in the detail of how the Hegemony works in rural areas, with lots of implications for what kind of order you’ll be able to put in its place. Witnessing the Telone’s efforts to impose uniform implementation of Karagon’s policies over a vast area, at the same time as you’re trying to guide your rebellion from a distance and get them to follow your policies, should bring up some nice resonances and foreshadow future dilemmas.
I’ll hold my decision and Ch 1 revisions until then, too. 
If it doesn’t look like it’ll work, I’ll go back to Plan A.
It was on track to be double the length of the first, and frankly, I was worrying about the higher price point scaring people away. I’m virtually at 600k words already, and by the time we’re done, I’m sure it’ll be longer than G1. Just not silly-longer.
It’s got extensive irrigation for a massive green area around it…but yes, when you get to the last irrigated field, you’ll be looking out on a treeless waste that (on any side but the northeast) turns before long to a grassless waste.
Being the climax of a big chapter was already taking its toll. I started writing knowing there would be a lynch mob ending, and suspecting that there would be a gunpowder plot ending. I’ve since discovered a “duel the Theurge” ending, a “slaughter the Alastors” ending, and an “Alastor Captain slaughtered in a duel (but not with you)” ending. The Storm follows you.
I’m planning to write more of it, yes.
Let’s see what the feedback is on the Irduin chapter, which has a “pick primary and secondary factions to hang out with” structure.
Choice of Rebels: Urban Planning
I wrote to my friend earlier this month still insisting I was on track to win it even if it meant one of the games had to be 2m words.
But since my friend’s the sharing type, I’ll console myself with a nice Balvenie, Oban, Lagavulin, or Ardbeg. That’s probably the order in which I’d recommend you try them, too – they get peatier and smokier as you go down the list, and that’s an acquired taste. (I’ve not been masochistic enough to properly develop a tolerance for Laphroaig, which sells itself as tasting of sailcloth and iodine).
While we’re on liquor recommendations, if you ever find yourself in Nepal (as one does), go to Bandipur and visit Samay Baji, a Newari restaurant there. Their homemade spiced aila is one of the nicest things I’ve ever tasted.
It’s an Oban question whether I’ll need to Bowmore to reality.