I think it is time to stop talking about Tizen as could-have-been and move to definitely won’t be.

–Anonymous Ex-Nokian, August 21st, 2014

That above is my best attempt to summarize the state of Tizen. Another good one comes from Staska:

Tizen is dead. Period. As is any new OS that tries to become something in current landscape. Currently we have Android, iOS and Windows Phone. After those come BlackBerry, Sailfish OS, Firefox OS and ALL others that COMBINED sum up for 0.6% market share.
With Windows Phone Microsoft has shown us what a herculean task it is to build up a new ecosystem when existing iOS/Android duopoly already exists. With all that hard work Windows Phone is now over FOUR times bigger than all the other challenging OSes combined – and still Windows Phone has only 2.5% market share.

That is after all the hard work of Microsoft. For Tizen which starts its work from zero, the window is closed. Perhaps if Tizen had existed in 2011, it could have grown into something. More likely if Tizen had existed in 2010. Very tough task to get anywhere in 2012. Close to impossibility in 2013. Understandably killed in 2014.

The reason I say that window is closed is that smartphones seem to be aligning to the history of PCs. We now have the de-facto OS (Android), like Windows became the default OS for PCs. Then we have Apple that has always been able to find space for itself.
As OS is no longer a way to differentiate, Android vendors will now start the race that PC hardware vendors (Dell, Asus, Acer, etc.) already have had. They use common components and battle on who is first to include some new feature or who is first to offer the new chipset. Then they all will fight the price war, cut margins and eventually they all will dream of the good old days.
I personally start to suspect that even Microsoft will eventually drop mobile operating system as a business, move their mobile-targeted services accessible from iOS and Android and when that is done, shut down Windows Phone. Or then they need to find an area where they can be profitable without having to gain big market share.

But for Tizen (or any other new OS) I see no chance. Seriously.
A new OS can find a niche market where one player (like Jolla) can be profitable. Maybe.
Someone coming out now and taking the place of “third ecosystem”? No. I don’t see it.