Your whole point crumbles due the fact they’ve stated it is going to be a temporary fixture, meaning they’ve planned for the case in which a populated server becomes too big.
Secondly, servers already have caps to them - you can still be in a Queue even with sharding due to an overload of players. (I recall Frostmourne on Legion and BFA launch)
I highly doubt blizzard has overlooked this issue, and WILL implement a cap on servers.
I assume this is an easy thing to do.
Their current servers are fine - they don’t need new ones.
If they optimised Sharding, and made it completely seamless - I’d be okay with it.
My issue with sharding on retail is that you experience that classic ‘fade out’ and ‘fade in’ effect, which decimates immersion.
A more predictive and dynamic sharding is another route they could go.
Say i’m walking out the gates of SW - it should shard me into Elwynn + Westfall as I pass the first statue leaving SW.
Meaning I will hear, and see players fighting outside before I get close.
Sharding gets a really bad rap - and I believe it is because of poor implementation and function.
It COULD be an amazing addition to classic - if it worked.
The only information we have is that Sharding will be used to off-load pressure (Which is completely reasonable) at Launch.
And that Sharding will only be used for a relatively short period of time.
I personally prefer no-sharding - but it isn’t sharding that is the cause of its terrible title of ‘bad system’ - it is Blizzard not making dramatic improvements to it.
Sharding would dramatically improve your Classic Experience if it wasn’t so poorly designed and didn’t break immersion 500 times a day.