It's commonplace to read / hear complaints about the artificiality of post-colonial borders in Africa. This sounds all convincing, that is until ...
|ethnolinguistic map of West Africa|
Tell me how to draw some much less conflict-prone borders there.
This region makes '90 Yugoslavia's border issues look easily solvable.*
I suppose the solution of such a chaos is probably to develop a concept of statehood and sovereignty that does not cling so much to territory and borders as we know it. Our concept of borders probably stem a lot more from rulers' interests than from institutional necessities.
Let's remember how during the high middle age ruling and exercising control, kind-of-taxation etc. were often defined by control over individual farms, not territories. A knight may have had control over one farm, a monastery about the other, yet another knight over the next and so on. They didn't need drawn borders as much as a modern state seems to.
The concept of territory-independent sovereignty and so on is probably most accessible when you look at minorities. Say, your nation's ethnic group has also many members in a neighbouring country, albeit as minority. You want peace and prosperity, so a diplomatic solution shall be found. Your nation agrees on a friendship treaty which among other things regulates exceptions, protection rights and privileges for the minority, including dual citizenship.
Combine this with EU-like free travel and work permits everywhere and the sovereignty as it affects the common people becomes largely limited to jurisdiction (which may be adapted to circumstances; see pre-1980 Lebanon, Native American reservations and so on), taxation (which is also often subject to treaties) and voting (no issue with dual citizenship).
Add a formal collective defence (alliance treaty) on top and there's very little need for state borders left. Even the elites may find such a system about as advantageous (exploitable) as a orthodox state.
I'm quite sceptical about changes of borders as solution to ethnicity-related problems unless it's about actual regional majorities demanding such a change. Most problems with patchwork maps as the above could be addressed much better through cooperation and rendering borders less important.
Why insist on all-powerful borders if you cannot find a satisfactory solution with them?
Cooperation to water down the problem potential of borders is -unlike violent attempts at altering them - consistent with the Charter of the United Nations. Europe has done a lot of field testing in regard to defusing the explosive potential of borders, it's probably about time to advertise this more as a promising approach.
The dominant theme of EU copying movements is "unification" or "unity", and this is probably the wrong keyword. Unification is probably not desired, while prosperity and stability through cooperation as well as the defusing of conflict potential might be more universally welcome.
*: Luckily, West African people tend to get much less agitated about nationalism / ethnicity than about social and cultural differences.