For all I know, my guild is not a ERP guild.
If you then say it’s a guild that has members who ERP… I am certain also the guild on AD where your female mage is has plenty of people who do the same.
For what concern the initiative, by itself can turn out great as concept.
I believe a player driven environment may be more vibrant and alive than the staticity offered by NPCs.
Albeit, personal experiences suggest me that the core roles will be filled in a way echoing of nepotism - to friends (and relative alts) - as it was for let’s say the correlation of Stormwind City Watch and High Court of Chancery (So Guards and Juridicial System in the hand of the same players through alts / multiaccounts / close knitted individuals).
Also as already noted by Karienn for different circumstances, the idea to exclude individuals or guilds is there.
In this thread I offered mutual involvement for a case in Duskwood ( [A-RP] In Defence of Duskwood - #12 by Albrecht-argent-dawn ), but the reply provided, to talk in game, happened after the interested person came, did his thing, and merely informed afterwards of what they did.
Plus ulterior conversations, listing which guilds to include in some local project, and which to eventually leave on the side or on ‘maybe’.
Thus, I can safely believe the concerns expressed above by third parties will reveal truthful on the longer run - even more so if a kind of answer is given on the forums, but then otherwise is done in game. Because forums are public, thus, a reply of façade.
Said that, I wish you best of luck in your project - which will require time and effort and is certainly taxating as anything of some magnitudo related to roleplay.