If you haven’t read MaRo’s article for today, you should probably before proceeding here.
The core of the issue: In the future, there will be two blocks of two sets each year, and they are dropping the Core Set. This also means there will be changes to rotation.
Well, at least this sheds a light onto why the Pro Tour formats were changed to Standard (before redacting the Winter Pro Tour back to Modern). Block doesn’t have enough cards to be a viable format for a pro tour anymore, so they should drop those. Of course, this leaves the Winter set in a pretty strange situation, as it won’t have the same emphasis put on it that the others do.
Loss of Core Set
I don’t think this is a big deal. I do think new players would rather have this set they know they are supposed to start with, but if so, its mostly the job of the LGSs and us more experienced players to show them the ropes. Its a hard game to start to play in a vacuum anyhow.
Of course, there’s the problem of Modern. Core Set was a place you could reprint random cards, such as [scryfall]Urborg, Tomb of Yawgmoth[/scryfall] and [scryfall]Chord of Calling[/scryfall] without having to justify them in a set. This price control mechanism is now gone. Not that they even used it that much, but some. Chord’s price has dropped to about a third of what it was before it was spoiled.
Of course, you could always put all sorts of random stuff in the core sets, such as Slivers, [scryfall]Ensoul Artifact[/scryfall] and the Souls, but I guess they’ll find a home eventually.
What this means for Core Set stables, such as [scryfall]Duress[/scryfall] and [scryfall]Negate[/scryfall] remains to be seen, although I’m guessing this will also mean more reprints in sets, as they will likely want known entities in Standard in the future as well.
Two Set Blocks
This is not going to be good for the story for those of us, who don’t really read the fiction. Story in two acts is not generally going to be very rewarding, but on the other hand, they didn’t really follow a three act structure anyhow, as the blocks were so top heavy.
What this does mean is more work for creative, as they need to come up with two worlds each year. However, there’s a way to mitigate this: Return to worlds more often. I guess they were going to do it anyhow, as they now have several worlds that are popular enough to return to (at least the worlds of the last five blocks, Mirrodin, Zendikar, Innistrad, Ravnica and Theros). Since many players are eager to return to their these worlds, this will probably be a good thing.
Also, no there won’t be that awkward third (or in case of Theros Block, second) set, which just can’t find its place in the whole. Some natural progression we have become accustomed to will be lost, but most won’t even notice.
Three-Block Format
I’m so over [scryfall]Supreme Verdict[/scryfall] and [scryfall]Sphinx’s Revelation[/scryfall] that I can’t wait for rotation. In a way its good to have something like that in a format to keep everyone honest, but they were simply too oppressive for a very long time. If rotation now happens twice a year, that’s going to be great.
After all, currently a bigger chunk always leaves than enters a format. In a month three big sets and a small one will be gone (over 800 card), while only one big set will replace them (229 cards). That’s pretty big. In the future, if rotation happens twice a year, we’re only losing about 400 cards while 230 or so come in. The flow of the format will be much smoother and even though the lifespan of the cards will be shorter, we can live with that.
Metagame
Hopefully, as they will be able introduce major changes twice a year, this will mean the metagame stays healthier. After all, Monoblue has been around Pro Tour Theros and is still good. UW Control has been around for majority of the year and its flash version was around even before the rotation. Monoblack has been around as well, although its results have been lagging as of late.
As someone who likes to test new things rather than slug through the same match-ups over and over again, this is going to be a great opportunity.
All-in-All
I think this is an excellent change. There will, of course, be problems at some point, but mostly they will be overshadowed by the positive changes.