But even Mozilla Foundation B2G will use html5 and B2G seems to be fast enough.

If you’re depending on the mobile operators to tell you what to do, you’re screwed before you begin.  The really successful players, like Apple or Google, don’t let the operators influence them almost at all.  Jumping on the html5 bandwagon as the cross-platform standard for mobile devices just shows how stupid the operators are.  HTML5 can still be too bloated for a desktop computer: forcing less powerful mobile devices to run such a bloated stack just shows they have no idea what they’re doing.  Tizen jumping on the HTML5 bandwagon in the hopes that they can get apps easily is just silly.  They announced an NDK at one point, which would have been very nice, but ditched it later on.

I’ll note that there is room for some sort of de facto standardization, but you don’t have to use web standards.  You could come up with native APIs that are abstracted to work across many devices.  Unfortunately, other than Apple, those pushing these platforms keep choosing bloated runtimes, like Java on Android or html5/javascript on webos and others, and having their performance gobbled up.  This is why Apple devices are the most responsive to this day and why they scarf up all the profits in the market.

It seems as many mobile operators want that Apps shall been in html5 as the WAC-association.

http://www.wacapps.net/press-releases/-/asset_publisher/v5Lg/content/wac-and-global-operators-to-drive-html5-adoption-through-2012-hackathon-series

But Tizen OS have an interesting competitor in Mer OS which is now in development in Merproject community.

Nokia have decided to change OS in their cheaper phones from Symbian to Meltemi OS which is like Tizen OS and Mer OS based on MeeGo.