My personal belief of what is going to happen in Dragonsteel, is that Hoid will destroy all the Shards and himself in the process.
Adonalsium was a singular, incomprehensibly powerful entity. When it was “shattered,” it split into 16 Shards. Each Shard is Investiture focused around a specific intent or aspect of Adonalsium’s original power. Honor forming a cognitive/spiritual presence on Roshar is not exactly the same as shards forming consciousness from Investiture. Shards already have a Vessel, and the “personality” of the shard is directly tied to the Vessel. Investiture itself is usually reactive or semi-conscious, but it doesn’t spontaneously develop intent unless there’s a conscious influence behind it. So Adonalsium itself wasn’t just a pile of Investiture, gradually “learning to think.” It was likely already a super-conscious entity. The shards inherited intent from Adonalsium plus the choices of the Vessels.
Dead shards don’t have Vessels to focus them. Investiture can linger and influence things, but they aren’t conscious in the same way. So the “brainpower” of a dead shard is extremely limited. They require a bond to the physical realm. Also, one other problem. As far as we know, Ambition is totally and completely destroyed.
Harmony is Ruin + Preservation. Hoid explicitly notes that when Shards are paired, the opposing intents tend to cancel and stabilize. Your point is correct that Harmony might be limited without other complementary intents, but there’s no canonical evidence that Shards can “meld” naturally beyond the Vessel actively choosing to merge Investiture. Even then, the risk is extreme (Ruin and Preservation managed because their vessels decided to work together to create Scadrial and were bonded that way. Odium and Honor also work because their vessel made an oath.) Remember, everything requires a Command.
Very good point.
Just call Adonalsium 'it'.