no ETA on it yet. i just started working on it and it'll likely take awhile since it's the conclusion. I'm anticipating the usual, which is a few thousand hours of dev time. it'll probably be fairly long but I wanna do it right.
In terms of saves, never use old saves after an update. If you click new game, you can just follow any prompts from there and it'll start you right at the end of the previous update. If there's any relevant choices to that specific update, it'll just ask you a couple questions to check those boxes again and you're good to go. You can't use the previous save but we basically recreate one in about 5 seconds