Hey everyone, I've just come back from a long-ish break from Magic and have noticed something that I'd like to discuss. Forgive me if this runs long. What struck me while reviewing XLN/RIX is that three cards use the text "mana of any type" as opposed to "mana of any color" (Dead Man's Chest, Dire Fleet Daredevil, and Hostage Taker.) All three of these cards enable you to spend mana as "mana of any type" for playing cards owned by opponents, which in the current standard is mechanically indistinguishable from the usual template. Three cards from KLD/AKH blocks (Gonti, Lord of Luxury, Naga Vitalist, and Vizier of the Menagerie,) also used this templating, but that meant something as they shared time in standard with cards from OGW with colorless costs. For comparison, fifty-one cards in standard use "mana of any color", and there are only four other cards in all of Magic's history whose current Oracle text refers to "mana of any type".
I see two possibilities here, but please feel free to correct me or to add more:
It could be the case that WotC re-discovered the "mana of any type" terminology in KLD for the purpose of paying colorless costs and, deciding to have a high enough density of pirates in XLN block to support an EDH deck, chose to past-and-future-proof these cards.
The second likelihood is that an upcoming set is planning to use colorless costs, snow or some descendant thereof, or some other form of mana entirely which cannot be generated by basics. To share a standard environment with the pirate cards, this hypothetical mechanic would have to appear in Core Set 2019, Spaghetti, Meatballs, Milk, or Cookies (which is now Core Set 2020.)
I feel that the first is unlikely, as no other tribe has this rider and it deviates from standard templating for marginal gain (affecting nine extant cards, and specifically allowing pirates to press-gang Eldrazi into service isn't exactly a flavor home-run,) leaving the second option as the stronger possibility. Beyond that I'm speculating, but I hope not baselessly. Dire Fleet Daredevil limits its ability to paying for instants and sorceries. OGW had plenty of instants and sorceries with Devoid, but only Spatial Contortion and Warping Wail have colorless mana in their costs. Hostage Taker cares only about creatures, but Dead Man's Chest works for all non-land cards. For the color/type distinction to be meaningful, the typed-mana mechanic would have to be much more prevalent than colorless costs were in OGW; this suggests a major theme, factional identity/strategy, or a major planar characteristic.
It is unlikely that such a mechanic would be introduced in a Core Set, and it sounds very much like Wizards is still unsure on how to deliver Wastelands for colorless Brawl commanders (meaning Eldrazi in Core 2019 are even less likely than they were to begin with,) so that leaves us with Spaghetti, Meatballs, and Milk in which to look for it. We could see as many as three new planes sharing standard with XLN/RIX if all the scheduled two-set blocks collapsed into one set, or as few as one new plane (if Dominaria part two were moved into the Spaghetti slot, and that plane had two sets taking over Meatballs and Milk,) so it is possible that any interaction in standard of the pirate trio with cards they'd care about got pre-empted by this shift if it was a Milk and Cookies thing, but my guess is that if there is something to this it will show up immediately post-Dominaria (else why design around it if the cards were going to rotate out at the next available opportunity?)
In any case, I haven't been able to infer much from this yet, but I do think that the argument that *something* is in the pipeline is compelling. Colorless costs returning as a faction demarcator in an artifact-themed set, a Mirrodin automata resistance vs Phyrexians or something like that, might provide the necessary volume of instants/sorceries to have Dire Fleet Daredevil make sense. Having Karn meet the Gatewatch certainly puts New Phyrexia back on the table after a long absence. I also think that hints of Viking-world/Kaldheim are being seeded for a near-future visit (the RIX storyline with Angrath returning home is cute, creating an in-universe reason for Magic vikings to have/emulate having horns,) but snow mana 1.0 mechanically is a mis-fit: snow mana hasn't yet appeared in a casting cost, which is all that three XLN/RIX cards care about, and presumably vikings or their allies would be snow-themed and not centered in WG, meaning you would have access to snow lands playing UBR anyway. Snow mana 2.0 would make more sense in this situation.
On a related note, this also suggests to me that planes with strong mana-base associations like Theros, Alara, and Ravnica (which is endgame for the current arc anyway,) are less likely to be coming up next. That's pretty much all I've got right now, but I'd be very interested if anyone else sees something in this notion.
I apologize for the wall of text; I still have the post-lapse glow, and noticing this got me to thinking. I'd also like to note that I did a search for discussion on this topic and came up empty; if I've missed something please feel free to relocate/remove this post.