Not to burst your excitement, but, this is not at all what this letter says. It says rather that the idea is "possible" but, as he correctly points out, you have a whole lot of logistics to consider first, and not just in terms of numbers of Touhou fans.
I mean it sounds like an exciting idea but I think you might be getting way ahead of yourself here.
Am-kun, I know what you mean. Considering I've been to a few Reitaisais myself, there's more to the event than just fans gathering together and cosplaying.
Primarily the whole point of the convention was just like to be a Comiket that sells doujin, music, figures, etc. from circles, have various events, and stuff, but to be separated from Comiket as a whole entirely(I mean having it have it's own convention). That's practically why a lot of fans go there, to buy stuff.
I never grew up in PH as a kid, and up to now I still don't know many Touhou fans in it(I don't even know much fans in AU either, until I met some other Strayans here. :V), but there has been some groups that sets up some events regarding it IIRC.
So we don't know how big this convention will be.
