agree that this is looking like the best path to strong AI. don't agree that the biological is the only potential path.
the biological path is only the best path while we share fundamental constraints with the brain.
The reliance on SDRs is likely linked to one of the bugs in our intelligence - the bias toward equivalence (the "IS A" bias). A hypothetical predictive system implemented without SDRs or with less dependence on SDRs might also be an intelligence that suffers less from the is-a bias.