I believe that the use of multi-utilities would be a good idea but the understanding between public and private utilities in the management of different services seems to be an obstacle. Paper by RT Silva, 2013: "The multi-utilities and the formation of horizontal monopolies of public services. Its impacts on urban management ", comes to a similar question as we speak on another occasion).
(What is Your opinion, which of the 3 ways is better?)
I would say that the smart grid incl. energy storage have still a huge potential to change the balance of power in the energy sector. ICT has affected energy business already and it will be difficult to change such course of events even though there are considerable threats regarding e.g. cybersecurity. The saturation of new technologies amongst energy utilities will come along and in this sense we can call such a phenomenon i-utility. On the other hand, I would not predict significant depreciation of large scale power plants in the nearest future (esp. after allowing public aid for Hinkley Point) Of course multi-utilities are different phenomenon raising controversions in antitrust and promising some benefits in economic terms...