What would happen if all shards where splintered.

[Devious he/him]

When a shard is “killed” they are splintered so if all of them were splintered what would happen to the cosmere?

[Calderis he/him]

The investiture would remain, albeit in smaller chunks. Depending on the way magic systems function It could have major impacts in some places and be barely noticeable in others. 

Surgebinding continues to function without honor, and I think in most cases things would keep going forward. 

Not sure if people could still be born with Breath on Nalthis... If they could then little change there, if not... That systems broken. 

The most interesting changes I think would be the emergence of new and varied kinds of a splinters everywhere. 

[Weltall]

Yeah, depending on how the Shards are splintered the effects on the different worlds could change and whether you'd really notice this or not would depend on the circumstances. For example, Sel has an extremely screwed up Cognitive Realm and location-dependant magic because of the specific way Devotion and Dominion were splintered and the aftereffects of the battle between Odium and Ambition has done things to Threnody even though the latter wasn't killed in that system. But Honor's splintering didn't break Surgebinding (from what we know the main effect was that it cut off the Heralds from their direct power supply) as spren are still doing their thing.

The Shards are godlike but they aren't like The Force in that they're binding the cosmere together so it's not like the universe would end if all the Shards were gone. Right now I'd be more worried about all but one particular Shard getting splintered in terms of how bad things would be for the cosmere...

[Agent34]

If there's something like spren on/around wherever the splintering takes place the effects wouldn't be too disastrous as shown on Roshar as opposed to Sel where seons and skazes couldn't fulfil that role and things got crazy from the wild Investiture.

[The One Who Connects he/him]

Relevant WoBs: One, Two, Three,

Quote

Leinton

If Endowment were killed, would the Returned still come?

Brandon Sanderson

Somebody needs to hold the magic. If no one holds the magic, the magic will start to gain sentience. Interesting and bizarre things happen then, so I would say yes, but with the caveat that with whoever picks up the power or what happens with the power could end up changing that.

Quote

"Q: You've said that Investiture tends to develop sapience on its own. Is this a function of the amount of Investiture alone (i.e. any pile of Investiture large enough will develop sapience eventually), or does the process require extra effort (e.g. a Command from an Awakener, an action by a Shard, etc.)?
 
A: Under the right circumstances, a pile of investiture will eventually become self-aware. But there is no specific timing. The more investiture clumped together, the more likely--and the closer to human-level intelligence it is likely to obtain. Of course, if you leave matter alone long enough (on a galactic scale) it will eventually end up becoming sapient too. So this isn't that different. (Well, okay, it is.)
 
Q: Are humans already sapient and intelligent because their Spiritual DNA tell their innate investiture what connections to make or what weird soul pattern to go into.
 
A: Let's RAFO that for now."

Quote

AonDor is based on the fact that the Dor, which is an amalgamation of Dominion and Devotion, has been pressed together and stuffed into the Cognitive Realm by Odium who didn’t want it to gain sentience, as Investiture will do if it is left alone. It will either seek someone to be its Vessel or it will gain sentience. He pressed it in there; he pressed it together, which creates the violent reaction, because those two Intents are opposed. And that is the foundation of the magic.

The last one implies that the drastic changes on Sel are a direct result of Odium's handiwork, rather than a natural consequence of splintering. This likely helps clear up why the magic didn't change when Honor was splintered