The rules for the 65th Sanremo Festival have been released and they include an interesting item regarding the Eurovision Song Contest. The article 27 of the Italian music contest rules say that:
The winning artist of the "CAMPIONI" section will have the right to participate representing Italy at the 2015 Eurovision Song Contest. In case they do not intend to make use of this possibility, the organizers of this event will reserve the right to choose the participants according to their own criteria.
The "CAMPIONI" section is the "established artists" category of the Sanremo contest. So basically this means that it's up to the winning artist to decide about the Eurovision participation and also about the song to be performed in Vienna.
Since Italy's debut in the European competition in the very first contest in 1956, Sanremo has been linked to their participations.
And in 2014 Emma Marrone and her song La Mia Città were chosen internally and sent to Copenhagen without a Sanremo connection. Coincidentally Emma was the winner of the national music competition in 2012.