Interesting thread. I've lurked here long enough to know what Bill Yao has been producing the last couple of years and in fact recently placed an order for a MKII Milsub (HRV) non-date.
I have peeked in from time to time to see the development of his Project 300. Names and marking are a large part of the aesthetic appeal and as such can be critical to the sales success of anyone's products. I see the need for a system to be used as opposed to naming each model each time.
I have broadly thought that P300 would be in an entirely different direction for this model and all the ones that succeed it. Develop an alpha-numeric designation system that can accommodate all future models as certain car companies have; Porsche, Ferrari, McLaren, and BMW come to mind. Nikon, Leica, Hasselblad and Canon also do that with there DSLRs.
P300 could only be the beginning. But of course because 100, 200, 300, 500 and 1000 are typically used to denote their depth rating so more variants can be produced in the future without the rush for a new name every time that may be fraught with legal issues.
P100
P200
P300
M100
M200
M300
R100
R200
R300
RS100
RS300
RS1000
or add the depth unit
P100M
P300M
M100M
M200M
M300M
R100M
R200M
R300M
RS100M
RS300M
RS1000M
Another approach could be deriving numeric values from case dimensions.
P38
P42
P44
R43
R46
RS46
And on and on ... but you get the ideas. Some combinations subliminally suggest fast cars, while others suggest firearms. Which may not be a bad thing. Again, it's so subtle as to be subliminal. One does have to push the automobile, camera or firearm connection.
Dial markings can become this in the proper positions of course:
MKII
RS300
300m/1000ft