Well it's confirmed that we're going back to Kamigawa next year- sort of. Gone is the feudal era, replaced by something that looks like Neo-Tokoyo. Perhaps it will draw a wider audience, and some of the traditional Japanese lore was sort of inaccessible for the average westerner.
Legend Mechanic- something like grandeur seems possible. While the set will possibly have a lot of legends, it seems like something that needs support.
Tribal- Kamigawa had several unique tribes and classes.
Snakes could come back as G/U. perhaps they'd get a piece of the ninja pie. something more than more +1/+1 counters. Green is sort of suposed to be the master of combat tricks, anyway.
Kitsune- I think they might have a k-pop theme this time. not sure about actual mechanics
Nezumi- Probably back as Yakuza gangsters. Perhaps the Oni are the bosses.
Samurai- Since it's not the feudal era anymore, they're probably gone.
Shrines- Perhaps they could be tribal shrines, that care about thier tribes rather than other shrines for instance
Ninja Dojo- 3B
At the beginning of your upkeep, target opponent loses x life, where x is the number of ninjas you control
Pretty sure it's common in the cyberpunk genre to refer to the warrior/soldier archetype as "samurai". It may not mean exactly the same thing it used to, but anything from corporate private soldiers to ronin mercenaries could fit the creature type. Now Bushido, that's probably gone, both mechanics and lore-wise.
While this set has cyberpunk elements, I don't think it will resemble traditional cyberpunk. This is still Magic the Gathering and this is still Kamigawa.
I don't think we'll see actual guns here, for instance, but rather similar to Kaladesh there'll be some more fantastical technological weapons alongside some classical fantasy weapons. I don't think there will be actual computers or phones or internet. I suspect, however, there could well be some fantasy styled version of computer and/or internet-like technology, likely magic involved. Like, what if you could send messages not using EM waves but using technology that taps into the spirit world or something? I expect there will be cyborg body augmentation stuff. We saw a version of that with Mirrodin and it seems a cinch for if this set was top-down at all to include transhumanist stuff. I don't think there will be modern cars or planes but I expect some vehicles including airships that are some combination of more old-fashioned looking and futuristic at the same time in a retrofuturist sort of way. Given we have New Capenna coming right up after, I don't think there will be much about gangs but instead I expect the magic equivalent of cyberpunk shady megacorps will appear, though I'm guessing they won't be referred to as corporations.
Also, I think Kami will still be a big part of the world, though vastly reduced in numbers. What I can totally see (and you heard it here first folks, this is my prediction, shower me in praise when it turns out to be true) are a couple cards playing into AI tropes, flavoured as Kami inhabiting synthetic bodies. *cough Ghost in the Shell cough*. It wouldn't be quite the "humans have created something dangerous" angle and more the "alien intelligence wants to be human" angle, which is fairly common in AI stories.
People might put all kinds of asian pop-music into the genre still.
I would think they go just a bit more about technology and the human culture in here, and ditch the entire "spirit" part more.
There might still be a faction in Kamigawa that is more about their former religion, with spirits in the mix, but spirits probably wont be a major part anymore, as the Kami-war is over.
Some equipment is probably guaranteed, even simple commons just for limited.
If they bring back Samurai, hope they leave Bushido behind--mechanic doesn't play well at all when you go deep on it. Combat math nightmare and mentally taxing...for a little flavor tradeoff. The more you play with it, the less you want to. (Was my experience, at least.)
I think Flisch's idea "Ghost in the Shell" is probably exactly where this is headed. That's a really cool idea and interesting way to pull this off. Pretty wild.
if we get dfcs, they could use energy to transform. or they might just stick to other conditions. outside of "play for fairly broken effects" parts of it, it seemed like it wasn't too bad. the idea that there was some energy source beyond mana was kind of interesting.