Hello Mark! If the rules baggage of legendary were removed, what do you think would happen to Mirror Gallery? Would the card do straight-up nothing? Would it get an erratum to give it any kind of utility?

There have been cards that basically do nothing with a rules change. It’s the cost of the game being able to evolve.

Why do we get a strictly better version of Mirror Gallery, but not an updated version of One With Nothing?

We can’t improve upon One With Nothing. : )

It's my birthday and all I want to do is spread my firm belief that Mirror Gallery should have been legendary while passive-aggressively insisting on a much-needed errata to that effect. Take care!

It’s the kind of joke that’s funny for those that get it and confuses those that don’t. We very seldom put words on cards that are never supposed to matter.

If I have 2 krark's thumbs in play do I flip 4 coins instead of one?

The card is legendary (to stop this very thing), but let’s assume you have a Mirror Gallery or something out. Yes, in that case, you’d flip four coins.

If Mirror Gallery had been printed more recently, do you think it would have had different wording instead of directly referencing the Legend Rule? Like, "You may control any number of legendary permanents with the same name."

Yes, it would be written differently if we made it today.

Was Mirror Gallery Ever considered for reprint in Dominaria?

We talked about it briefly.

Is the rule for legendary sorceries considered part of the legend rule? Like with a Mirror Gallery in play, can I cast as many legendary sorceries with the same name as I want?

You can do that without Mirror Gallery.

If you made the Unique keyword, and errata'd it onto problematic legends of the past, like, say, Krak's Thumb, would Mirror Gallery remove Unique?

In theory.

Why would removing the rules associated with legendary be a problem? While it would make some cheap legends really good and Mirror Gallery useless, it isn't like those rules haven't changed multiple times anyways. Braid of Fire becoming a lot better without mana burn didn't seem to break anything, and even if it did, the relevant cards could just get banned in formats where they're a problem.

My thought on the matter is a minority opinion in R&D. The majority are not interested in the idea.

If the legend rule were to be abolished, what would Brothers Yamazaki and Mirror Gallery actually say on them?

I don’t know. We’ve made rules changes that have essentially made cards do nothing before.