Well,hopefully clever marketing will also allow people to rent
  out portions of our living brainspace as well. While the "only
  10% of the brain" is a myth (we use 100% of our brain) -
  nevertheless, I could see it being a source of income for people
  in the future, much as we allow companies to make use of our
  time when they show us advertising and such. Exactly. It's not
  "right" but it happens. As long as we live in a capitalist
  society.. and unfortunately I don't see anybody in positions to
  change it wanting to do anything about that, it's likely we'll
  _still_ be in some kind of capitalist society when technology
  catches up to our ideas expressed here in 2015.

  An example of how we do it now though: Facebook

  Facebook isn't free. It's paid for by advertisers.

  We allow the advertisers to take up screen space (and brain
  space because we see it) - in exchange for not having to pay for
  Facebook ourselves.   It seems normal to us now. Renting
  brainspace in the future will likely be a similar scenario. It
  will appear so everyday and normal that we won't even think
  twice about it.