I'm seriously thinking of taking a research break as soon as I finish 16, just to feel the F-R-E-E-D-O-M from guest races again.
I honestly wish that Inno would get off the guest race kick and just have ONE later chapter in which a whole new concept is tried. No portal. Just incentives and special quests to optimize your city on the path YOU choose ... for instance, let's try this scenario: The first quest tells you that there is a new, dangerous race populating the regions nearby and you must mobilize to either fight them or negotiate with them. The quest asks if you wish to be a Trader or a Fighter, and then tailors quests for you based on that option, to "superpower" your city to do one or the other, with a new AW to match your choice. The storyline unfolds to tell you how your enhancements are helping in the confrontation with the new race. But that new race isn't a guest race in your city ... just you fighting or negotiating with them and building up what you have. Anyway, I'd like that, even if no one else would.