Watch out Spotify and iTunes, YouTube is apparently jumping on board with the on-demand music model later this year. The video platform is planning for a service that will offer free and premium listening options across devices. The free version is expected to include ads, but, unlike Spotify, also offer on-demand tracks via the mobile platform. The premium tier is thought to remove ads and have offline listening. It's speculated that Google, which owns YouTube, might be interested in pairing this service up with products like Google Glass in the future.