Brain science is my expertise, and you're right that the lack of vasculature will limit the viability of this. It will never grow beyond a few mm, and will have a dead core most likely. Plus, at "5 weeks" there will be no astrocytes or oligodendrocytes. You need astrocytes to make proper synapses and oligos to get proper signalling speeds. Others have shown more advanced brain organoids, incl astrocytes, but this tech is still very far from a conscious piece of tissue in a dish.