Yes, There's no way that Standalone will completely ruin the servers for the mod(for now at least). There';s no way that everyone is just going to play vanilla DayZ for however long it takes for a full, mostly bug free game to come out. I think the smaller mods like Civilian will suffer(even more) but the bigger mods like Overwatch and Epoch will take a long time to die down. Maybe a year or so. I do see your concern though