I'm also really concerned about the change.
I mean, the new version looks pretty cool – I always enjoy watching nice infantry sprites, water and really cool navy vessels roaming on the map etc.
Though, when it comes to actually playing against real opponents I always switch to legacy. It’s way more convenient to make orders and shows units exactly where they are. I cannot imagine sticking only to the new version, especially without a tactical mode.
I‘m pretty sure, that the reason that only veterans/older players prefer legacy mode is not because they used to and don’t like changes but simply because the new players don’t even have the option to try it and compare.