I am not convinced there was an implied agreement to preserve secondary market prices outside of the Reserved List, at least for cards which are Modern legal. As you mention in the article, one of Wizards' stated reasons for establishing the Modern format was to have a non-rotating format that wouldn't present a significant price barrier to entry. I think it's pretty clear that this constitutes an announcement by Wizards that there is no promise of value retention in Modern-legal cards, that what has been true for cards before Modern is no longer true. In this case, there isn't merely an omission of a verbal/written contract; there is a stated rejection of such a contract. Wizards essentially said, with the Modern format, "We are providing these cards but you are hereafter warned that they are open to reprint at any time."
That being said, I can't help but wonder if there is a point where enough time has gone by, much like a statute of limitations, where that original statement becomes invalid. Even though Wizards appeared to intend this to be the rule for Modern, they have not really lived up to that. Personally, I consider the low price barrier concept an essential point of having the format. However, we now live in a time when certain cards in Modern cost more than the expensive cards did in Legacy at the time when Modern was created.
I honestly think Wizards should consider banning cards from Modern purely based on their price having risen too high. Either that or do a real reprint of these cards (Modern Masters doesn't count because the price per pack still presents a significant price barrier).
Isolated Chapel = Whiterun
Sulfer Falls = Markarth
Woodland Cemetary = Morthal (I know, this one's a stretch)
Clifftop Retreat = should have been High Hrothgar goddammit
Really the only two that are "broken" are Time Spiral and Palinchron, and the latter I'm not even 100% sure about.
I played mono-blue in Urza-Mercadian Standard. The deck did not even have a full playset of Rewind.
Overall, this was yet another game mechanic that WotC totally overreacted about. In fact, with creatures experiencing the power creep over the past years, I don't think cards like Peregrine Drake or Great Whale would be particular outstanding in Standard today.
That said, I'm still very impressed that they printed this, because they have been so opposed to this mechanic for so long. And I think this is actually quite playable in Standard or perhaps Modern (we'll see).
EDIT: Also, I think picking up a foil set of these early is probably a reasonable thing to do.
This, (and Rewind) do not help win counter wars. You don't get to untap the lands until this resolves. If they respond to this with a counter of their own, the lands remain tapped while you decide if you want to then play a second counter of some type.
Instant speed card draw, which blue has available in Standard right now in plentiful quantity: Opt, Hieroglyphic Illumination, Pull From Tomorrow, Glimmer of Genius, and Supreme Will. Also goes well with Gearhulk. I think we're going to see quite an impressive last hurrah of Monoblue Gearhulk decks, and this will probably be a part of it. Also, kind of cool that casting this off Gearhulk gets you half of Gearhulk's cost back. I'm looking forward to the day when I cast this to counter something, then flash in Gearhulk and recast this to counter another thing the same turn, and then end of their turn cast Opt or Supreme Will or whatever.
This effect, not really seen since Urza block, was considered a "mistake" and now we have a card that isn't even "strictly worse" than Rewind.
Might even show up in Modern, but I dunno, 3 cmc is cutting it hard there.
Might have been more reasonable if it were a Thoughtseize kind of effect.
EDIT: Oh, I see, it looks like the OP copied the text from the original Antiquities version, which was common.
Sage of Lat-Nam is a reprint that was already legal in Modern, having been reprinted in 8th Edition.
EDIT: That was supposed to quote both posts before mine.
Well, I think if you look at that issue, you will realize that we're assuming that an aspect of expansion sets is the way it is only because it's always been that way. But we've seen evidence of the contrary. New cards don't have to be legal in Standard.
Commander sets are legal in Legacy and Vintage. They add new cards to those formats, and those new cards never have to worry about "passing through Standard". So with that in mind, they could create a set where the cards are legal in Modern, Legacy, and Vintage, but not in Standard (Unless it's something already legal in Standard). They could use this set to reprint all kinds of things that would be great in Modern but cause problems in Standard. They could even print new cards specifically made to match the power level of Modern without worrying about how they would affect Standard.
I mean, hell... they could release a set containing new cards only for Vintage, on the same power level as the cards that make Vintage worth playing. Not saying they should, just that there are a lot of options here. The idea that the cards would ruin Standard is based on a faulty premise.