Putting iTunes on Samsung and other Android-based smartphones is not about selling music, it's about selling wearables. Apple put iTunes on Windows to sell iPods to PC users. It created a halo effect with PC users switching to Macs, then the iPhone and iPad.
With their foray into multiple new product categories, as CEO Tim Cook puts it, Apple will need software for Android with which an iWatch, or iBand, or wrist-worn iPod Nano can communicate. In 2004, everyday consumers, not technology nerds or gadget heads, synced their iPods with their Dell laptops. Then they bought Macs after learning how much they liked Apple's products.
The same can happen in 2014: everyday people will buy an iPod Nano for their wrist and sync it with their Samsung smartphones. This is why iTunes needs a subscription-based catalog similar to Spotify, most Android users have never used iTunes, let alone ripped a CD.
Game over, Samsung? We'll have to wait and see. I'm getting my popcorn ready.