Tizen, which is Samsung's own mobile operating system. Is due to get a pretty big upgrade this September, as Samsung announced at their developer conference in San Francisco this week. This update is actually going to be a rather big one, and according to reports, it'll be more competitive with Android and iOS. Tizen, was Samsung's way out of Android. However currently it hasn't really gained much ground and is really only competitive in the wearable space with their Gear lineup.
The update to Tizen 3.0 will make the operating system 64-bit, which again makes it more competitive with Android and iOS given that both are already 64-bit. And Samsung stated that it'll be coming on some new devices that are 64-bit ARM and x86 processor powered. Samsung is putting out the beta in July, where developers will be able to start playing around with the updated Tizen and get their apps working on it.
Tizen hasn't exactly taken off for Samsung just yet. They launched the Samsung Z1 last year, which was a fairly inexpensive smartphone, but it really didn't sell well at all. However Tizen is running on the Gear S2 smartwatch as well as the Gear S and Gear 2 smartwatches. But Samsung's not giving up on Tizen just yet. However, if they don't start to gain some ground soon, they may just keep it for wearables and Internet of Things devices.
Right now there are two dominant mobile OS, which are Apple's iOS and Google's Android. Android has a much larger market share, but they are the two behemoths around right now. We've seen other mobile operating systems attempt at being successful - most notably is perhaps the Windows Phone from Microsoft. Which has never really taken off. Then there's also Firefox OS, as well as Tizen. Which shows us that the market doesn't have much need or want for a third mobile OS. Especially with many smartphone users not wanting to switch from one platform to another - particularly due to apps, games, music, etc., being rebought on the other platform. Definitely not something most users want to deal with.