Xcode 10 or not, you should make sure that the "additional software" like the NIK filters, which has already been bought at a high price by many, is still compatible. I don't know anything about programming, but I think the rewriting of the program happens because of more future functions. We all appreciate that - but obviously, many experienced AFP users are not as satisfied with 1.7 as you would like it to be. You have to take that into account. Instead of creating only a - required - bugfix of AFP 1.6.7, rewriting the software is a risky step. Some filters have been rewritten so that they are no longer useful in my case (e.G. Denoise, Clarity) - but I'm not the only one complaining about that.
Best regards, Puck (still a fan!)