I recent engaged in a point/counterpoint debate with my friend and colleague Michael Finneran on the subject of whether Samsung will eventually drop or at least augment Android with Tizen. You can read the full debate (the link above) yourself, which makes all of the points I think are worth making. While I'm going to agree that completely abandoning Android wholesale would be risky, absent a long-term staged or dual-platform strategy, anyway, I still contend that Samsung must further differentiate itself on the way to establishing its own ecosystem. All of the market leaders - Apple (in particular), Google, and even Microsoft and Amazon, understand that many ("all" is still a bit of an abstract concept here) elements of the solution puzzle - hardware, software, distribution, applications, content, and more - must be under their control. Being a supplier of components no longer works; consumers want end-to-end thinking and one-stop shopping.
Samsung is #1 in handsets and a huge conglomerate diversified in a broad range of proprietary manufactured products well beyond what any of its competitors in the IT space could ever hope to be. If anyone can make Tizen fly to their benefit, it's Samsung; they've even got an effort underway to attract apps. Yes, there's risk here, but even more if they don't own their OS.