Sadly, I’ve come to the same conclusion. It’s not simply the immediate impact on the game in general (which is bad enough), but the fact is if sharding is in at launch players will ask for it a week later. And a week after that. And then a month later. And in any circumstance where they feel inconvenienced. And can you blame then when Blizzard already caves in to that mentality?
I’m not going to put myself in a position where for the entirety of Classic this will be an issue to have to worry about. The devs simply need to prevent it from ever taking root, because once it does no amount of Roundup will kill that weed. Oh, and it might give you cancer too.