I don't think language barrier would be all too big a problem; these days, nearly every civilized country has their kids learning English since elementary school.
Cultural and playstyle differences might mean trouble, though. The resulting server would either have to open three different Uni channels and chats (eventually resulting into three separate communities forever locked in a state of "cultural rivalry"), or it'd have to adopt English as an official language, which would be unfair towards Germans and Frenches, because the current inhabitants of English server would naturally expect other communities to adopt Arispotle rules and customs as well. German and French communities have their history, as rich and valid as the one of Arispotle community, and they deserve to keep it.
Unless it's a choice between merging the shards OR closing Ryzom, I'm against merging the shards.
Cultural and playstyle differences might mean trouble, though. The resulting server would either have to open three different Uni channels and chats (eventually resulting into three separate communities forever locked in a state of "cultural rivalry"), or it'd have to adopt English as an official language, which would be unfair towards Germans and Frenches, because the current inhabitants of English server would naturally expect other communities to adopt Arispotle rules and customs as well. German and French communities have their history, as rich and valid as the one of Arispotle community, and they deserve to keep it.
Unless it's a choice between merging the shards OR closing Ryzom, I'm against merging the shards.