[keyboardP]

Why would Samsung want to suddenly switch to a Nexus device when they're dominating the entire Android market with the Galaxy brand? Most users don't know what version of Android they're running, let alone worry about what stock Android is or whether or not an update is available. In fact, now that Samsung has a greater brand name than Android, they can be more confident that their Tizen project will have a greater head start than if they hadn't started with Android initially.

You're looking at it from the angle of a tech consumer, not a business. They've done very well with their Android strategy considering the marketshare it has. Pretty much all Android users will be using at least one Google service which generates revenue or signed up to Google services that will tie them to their ecosystem.