I don't know. I get what you are saying, but in this particular case they might actually go with the old, confusing layout, if they decide that this is what those who are asking for classic servers want (and I think that yes, this is what they want - the old thing, with the old quirks and gotchas and secrets).
But more importantly, I think they will do nothing at all for classic servers until Legion is stable. And it does not look to be stable just yet, things are looking pretty dangerous. So, I guess already said it, but I will quickly repeat it: I think we will have no news on classic servers or TBC servers or whatever else other than live for at least a year. The only news this thread will get in the next year - in my opinion - is if Blizzard decide to close the server that should not be named 2.0 or some other server like it.
PS: Obviously, the "frankenstein" scenario you describe is a no go. It serves nobody.