Fantastic that there will be multiple spacebar support.
MX stems for stabs is fine but it pretty much means these caps will be for Alps versions of modern boards...which is very much needed.
I think a large base kit makes sense. Alps lovers are definitely a subset of the keeb community so there might not be enough of us to support lots of kitting options.
Frankly, most people buying GMK end up with a bunch of caps they never use anyway (numpad...I'm looking at you), so I don't think it should shock anyone to have a DCS Alps set that includes keys that some might not need (e.g. ISO vs ANSI).