The idea of Autonomy being a collective, or of Bavadin splintering their mind like Shallan, has always rubbed me the wrong way. I feel like we're still a long way from understanding Autonomy's intent (and how it's able to reconcile it with violating the autonomy of other shards by meddling with their worlds), but this still struck me as unfitting.
This theory interests me quite a bit, because now that I think of it, there's no reason Ambition (or at least splinters thereof) shouldn't have gained sentience by now. The only reason the Dor hasn't is because it's trapped in the pressure cooker known as the Cognitive Realm, keeping it as what Sanderson describes as a "hot plasma", which doesn't sound conducive to forming consciousness. Ambition, however, was left alone after it's vessel was killed, so far as we know. It totally should be developing consciousness, like Sanderson has told us uncontrolled Investiture does.
As for why it would form a collective, rather than separate consciousnesses like the spren of Honor or the seons of Devotion, perhaps it's because being in the depths of space meant there was no human thought giving them shape in the way that the Rosharans shaped the spren. Instead, the bits of Ambition each formed a consciousness, but still considered themselves to be Ambition, instead of embodying some concept. Thus, we would end up with multiple minds who all consider themselves to be extensions of the same entity.
I'm still not sure exactly how I feel about this theory, but I'm intrigued.