Agree totally,
The 15202 is classic but the 15400 is an evolutionary progression, as is the 15500.
Having 15202 and 15400 would not be redundant if you are an AP lover. The look and feel is quite different. 15202 is more of a dress watch while the 15400 is decidedly a sport watch. A 15400 and 15500 would be more redundant.
I feel the 15202 XF is leagues beyond what was previously available but I might wait personally.
The 15400 ZF is almost excellent as is (I have minor complaints about the bracelet finishing).
For me having a more refined 15202 and a decent 15500 rep would be an ideal combination. I’d love to own a gen 15202 if I could, and I might own a gen 15500 some day. The 15400 ZF makes it probably makes gen ownership less exciting— sorry AP, but that’s why you had to do what you did with the 15500. You saw this day coming just like the rest of us.
It may be sacrilegious to say so, but I think that next to the caliber 4302 used in the 15500 and even the 3120 used in the 15400, the 15202 movement feels a little outdated, if you look at how the date is set in the 15202. I do agree that the 15202 makes a better dress watch than any other Royal Oak model based on its thickness and overall elegance.
And yes, the 15400 has been very well repped, and with the diminishing visual distance between the gen and rep, one will need to carefully consider purchasing the 15400 if it is meant to be worn only for visual admiration and satisfaction.