You essentially argue that the alliamce system caused the WW1 but I don't think that argument works very well. An alliance system alone does not cause war. The questiom is why within a given international situation some people start a war.
The reason the relation did not change was not just Alsace-Lorraine, there are other issues. So I really think it can not be called a root cause of WW1.
I suppose it comes down to whether you're arguing what started the war or what started the world war. Without the alliances, Austria-Hungary would have invaded Serbia and that would have been it.
You essentially argue that the alliamce system caused the WW1 but I don't think that argument works very well. An alliance system alone does not cause war. The questiom is why within a given international situation some people start a war.
The reason the relation did not change was not just Alsace-Lorraine, there are other issues. So I really think it can not be called a root cause of WW1.