With the demise of core sets comes the end of seeing plane-specific-flavored reprints in regular sets that don't actually take place on or reference that plane. This means that some beloved cards seem to be consigned to the dustbin of history - or not quite, as Mark Rosewater made clear answering a question on his Tumblr blog recently.
When pjweisberg asked, "What will become of my poor Serra Angel? She doesn't make sense on any world where Serra's never been, and Serra isn't visiting any new worlds any time soon. :-(" Rosewater responded:
Don’t forget we are still going to make some products for beginners and things like Serra Angel can be there.
The elimination of core sets, therefore, is going to allow R&D to make the game more accessible. Magic Origins might be the mystery "product for beginners" that Rosewater is talking about - Magic hasn't had a newbies-only set in ages, preferring to acclimate them with intro decks, the core set, and Duels of the Planeswalkers, but R&D has surely learned from the mistakes of both Starter and the Portal sets. Hopefully whatever the new product is, it allows new players to dip their toes in and not be scared off by the complexity of the game and the vastness of its history while also not patronizing them.