Are diaspora in (whatever place) reached or unreached?

Dear Justin,
I work with the diaspora in (x place), an unreached group…
Whether a specific diaspora group is ‘reached’ or ‘unreached’ is an interesting question that encapsulates some of the challenges with the definition, and measuring it.
Remember, when we use ‘unreached’ in the technical missiological sense, as defined in the Chicago meeting, it means: ‘a people group lacking a church that can evangelize the group to its borders without cross cultural assistance.’ Or, to boil it down succinctly, a reached group is one where the locals can do the job without outsiders.
‘Reached’ doesn’t mean outsiders are unwelcome, morally shouldn’t be there, or have nothing of value to contribute. It’s strictly a statement about the capacity of the local church.
So, are diaspora peoples reached or unreached?
The first challenge is asking about the people group itself. Take, for example, Somalis in America. Are we to consider them a distinct people group on their own, with their own culture? They share language with Somalis in Somalia. The Somalis in Somalia are clearly unreached. Does that mean the Somalis in America are, too?
One way to answer this is to ask whether the Somalis in America have an indigenous Somali church capable of evangelizing the Somalis-in-America group to its borders without assistance. If not, then the group is ‘unreached.’ If yes, then the group is ‘reached.’
There may be times when the home group is one status and the diaspora group is a different status. For example, many Iranians in the United States are Christians who have fled Iran. I don’t know the specific situation that well, but it’s possible that Iranians in America may be “reached” while the ones at home are “unreached.”
The reverse could also, in certain instances, be true, I suppose–if a group of unbelieving people from a people group that is marginally Christian are found in a place that is very non-Christian – for example, say atheist Americans in Saudi Arabia – who are cut off from any Christian influence because of their language, then its theoretically possible for them to be unreached. That’s more an armchair exercise; I can’t think of any situation (except very small possible pockets) where that might be the case.
A slightly ‘grayer’ area would be diasporas that rotate in and out – for example, international students. A student may only be in the United States for a limited time. Is he ‘reached’ while he’s here, and ‘unreached’ when he returns home? (Saudis studying in the United States spring to mind). And if he is to be ‘reached’ here, how do we do that – how do we plant a church amongst the Saudi students who are here which continues to reach all the Saudi students as they cycle in and out?
That takes thinking outside the box. I’m not sure there’s necessarily a ‘certain’ and ‘correct’ solution. I would more quickly go for the simpler and more obvious solution: Saudi (and all international) students ought to be invited into American homes, befriended, cared for, welcomed, helped. That might not be ‘reached’ in the technical sense, but it would be ‘reached’ in the active sense.