Even though this is getting way off topic for this thread now, I highly doubt they're going to add a face with more complications to existing watch models, simply due to the additional RAM and CPU requirements of having more apps running/being queried regularly. Every additional complication is another app that needs to be kept in memory and periodically woken up for background processing.
The "Colour" face has the ability to run 4 complications on all current AWs, whilst the "Modular" face can run 5 on all models. The current watches are easily capable of running the required number of apps because they already do - it's just a pretty poor selection of it.
We don't need new hardware for WatchOS5 to add new faces. There's no new functionality being asked for - just more skin options.