Battletag: Ravnecks#2964 Region: EU Trade Only?: Yes, you go first
Done with Bennixus#2520
You don't get the cards in the core set, you just can use them for free.
If you only play standard you can safely disenchant all basic and classic cards when the changes go live.
But if you want to play other modes like classic, wild or duels you shouldn't disenchant them.