I wouldn't be surprised if it ends up something like Smash 4's ZSS' nair.
I don't like this perspective (and no one needs to point out the bias for this).
Zero Suits nair is 10f (as is Ike's) start up and between two hits has 4 frame duration of hitboxes. It had disjoint but on tiny/thin lined hitboxes. it's blind spots were numerous. It required you to land with it (i.e. full air time) to get good use out of it. It's range horizontally behind is much worse than the front and it doesn't hit low behind her either.
I have no idea what Ike's nair duration is now, but it's definitely covered with larger hitboxes, range, disjoint and area of coverage.
The theory that it's very vulnerable to parries (which isn't wrong per se) is what's going to keep it from being low-mid level players beating 'better' players because they'll be predictable with their spacing and timings. Ike doesn't have to just land on top of you with this move (and Ike just landing on top of me with this move is going to get up-b'd or up smashed oos by ZSS for free, I'm sure everyone's going to learn their bnb oos otions for dealing with ike nair pretty darn quickly). MKLeo's adaption to samsora legitimately seemed to be "oh i guess i have to think about where and when I time my landing nairs now" (and not just relentlessly using it over and over again like he was able to get away with vs most other people we saw) and suddenly the 5-10 frame duration landing move with an 8 frame safety window for parrying suddenly becomes a 1-2F window with spacing, and about 10+ different variations of timing and spacing from an Ike's execution with it.
MKLeo deserves credit.
Every player who's ever pushed an "OP move" or character tends to deserve credit, because for the most part the developer's aren't silly enough to create anything with 0 units of counterplay. But when you have really strong players using moves with maybe 1 unit of counter play but with smart usage goes down to 0.1, you're going to get broken/busted results.
Meta-wise, Ike could be good for everyone.
The meta is already significantly focused around using light weights.
Ikes combos are very dumb on lightweights, the base knockback of up air and nair puts lightweights into the death zone very easily, heavy weights on the other hand do not have to deal with this as much, and tend to have strong edge guarding options vs ike's side-b and up-b (flame throwers, charge shots, up tilts that are 2x as big as ike's nair, etc).
It's disappointing that Ike's nair is overtuned in relation to his kit this drastically, I don't think anyone could really argue this.
I believe it's a shame it's
that easy to combo off of it with essentially no DI mix ups existing (that we know of thus far). It probably should keep it's safety so Ike can maintain how threatening he is.... but perhaps it's growth needs to be higher so at least there's a point of time where you'll actually travel too far to combo into up air at ko% (again, heavies might already be in this basket, which firmly points towards Ike's nair not needing nerfs at all).
Can't wait for people to see someone good use [Dark] Samus' nair a lot and complain about it too.
At least that move sends horizontally instead of vertically, but truly, that move is glorious.
And when MKLeo says Dark Samus is a cool character he wants to use at top level, I'm pretty sure I see RIGHT THROUGH HIS CUNNING PLAN for when he does crack her out against someone's Ike, thus gratifying our friends like Minordeth who argue there's no foul to the move.
Ike can barely nair or EVER EVER jump against Samus thanks to her nair.
That's my take.