Hearthpwn

With the arrival of the core set, I initially thought that disenchanting duplicate copies would be okay. I'm sure a large portion of players already knew this if they kept up with patch notes and whatnot (I didn't because I was more of the mindset that I'll figure things out when the expansion drops), but Core cards are only useable in standard/wild and they rotate meaning they won't be in your collection once they rotate. The classic versions of your cards are useable in the classic format unlike core cards and will remain in your collection permanently as they always have.

TLDR: Don't be an idiot like me

we learn from our mistakes,good thing you try to help others, even though by now it's either too late for most or already known

Since they’re gonna give the core set for free every rotation, if you only play standard and you don’t care about collecting then dust away.  If not then don’t.