Apple is considering launching an on-demand streaming service similar to Spotify in light of declining music sales, reports Billboard. The service would be part of a multi-prong strategy that may also include an iTunes app for Android.Apple has opened exploratory talks with senior label executives about the possibility of launching an on-demand streaming service that would rival Spotify and Beats Music, according to three people familiar with the talks. Apple is also thinking about adding an iTunes App for Android phones, the Google rival that has been growing faster than the iPhone, these sources said.In January, it was reported that music sales