My advice is to not go full RAW on it, or really anything. Yes, the wording "technically" allows it on both ends since Elven generalist specifically says it replaces the ability to specialize in a school (not a domain) and that a domain wizard can't also be a specialist, which the generalist is not.
However, they are very, very clearly modifying the same class feature and ACFs that modify the same class feature overwhelmingly prevent it from being modified another way because being able to stack ACFs on that same level was definitely not intended. It's getting something for nothing. The only reason this combo comes out is because UA sometimes doesn't have the standard wording to prevent using other ACFs and the generalist ACF is so different.
Here's the book ACFs if you want to look through them and see for yourself how many ACFs prevent another ACF from modifying or replacing the same ability or feature.
Here's the Dragon Mag list too if you want it.
Might it result in something interesting and fun? Yes. Does it comply with the spirit and intent of the game? If sticking with the combined rules and spirit of the game, no. Should it be used in a handbook or guide? In my eyes, only with the caveat that almost all other ACFs have wording that prevents that kind of combination and in keeping with the spirit of the rules it should be noted as not working. RAW is not some holy scripture to always be taken with pedantic analysis of word semantics.
And yes, I'm a bit biased against this since a certain poster with the initials CJ made extensive use of this (among other things) and belittled people for not having the same point of view.
