That would be impressive uptime for both power and wireless connections. I was under the impression that autonomous vehicles would be more autonomous than that. Else what happens should something like http://www.usatoday.com/story/news/nation/2014/07/01/chicago... occur?
In any case, we're starting from the position that there are commercial parking services.
For your proposal to work, as a way to get rid of "companies like Impark" we have to assume that either that 1) street parking as you suggest will be free, ie, subsidized by the tax base as a whole, or 2) the city does not contract/sell operation of the central traffic planning system to companies like Impark.
Chicago (to mention it again), leased out its meters to a foreign corporation for 75 years.
If we wanted that now, we could nationalize all of the commercial parking systems. We instead often see the desire to find more revenue sources.
BTW, it won't be as simple as having a sign. Some areas already are free parking between given times, except during a declared snow emergency, or during hurricane evacuation. I'm not saying it can't be solved, only that it's not simple.
As traffic dies down in the evening and overnight, fewer lanes are needed. Some lanes could be deallocated from traffic use and allocated to parking use to hold cars overnight, and then put back to traffic use in the morning.