Don't worry, Apple has a lot of "HTML5" features that the other mobile platforms don't. Embrace and extend.
This is exactly what bothers me: Talking about open standards and then making their own versions of them. The Redmond strategy.
Makes me want say the same comment about Jobs open standards sweet talk as he made about Google's slogan... That's BS.
They can totally CONTROL what html5 can do in their devices.
More importantly they can control how well it does what it does.
If you have an iPad, check out http://touch.sproutcore.com/ and http://touch.sproutcore.com/hedwig/
The HTML5/JavaScript layer is already working very well, and Apple is investing time and effort to making it better. (Learned about those demo apps at the most recent JSConf in D.C.)
I don't think they see HTML5 as a threat to "Apps" because there's no way now or on even the distant horizon to sell HTML5 apps via a single tap.
They'll focus on making iPhone OS the best mobile HTML5 platform.