Some of the technical requirements, for an exocortex in the most simplistic form Alice just needs to have bots. These bots are agents, and Alice would simply ask questions, delegate tasks to these bots. These bots form a network, and could seek answers, services, or solutions from other bots or from humans. These bots can be built on Steemit even now so that part is not technically sophisticated.

Alice also would require access to a shared knowledge base, as well as having her personal knowledge base. This way a knowledge economy can form. This part requires linked data, rdf, reasoner, etc. The Cyc project is the closest thing to it, but for the most part this is the most technically chllenging part. The ability to actually create knowledge, to structure the data in a way which symbolic style (logic based) AI can reason over it.

Alice requires privacy, the ability to control her data, her knowledge base, etc. This privacy component may be possible through homomorphic encryption but in my blog I just called it advanced cryptography. Theoretically it is possible but performance is still very slow until CPU power improves.

All in all I think it can be built but the funding currently isn't there. More focus is going into small picture projects with some exceptions. Enigma is trying to solve the privacy part by building the homomorphic encryption I speak of and they have pretty good funding.