Sorry, I'm going to play the "greater good" card here. Yes, it's a shame if/when your project gets canned. The important thing here is that the masses will not be stuck with proprietary crap.
The web just jumped back a decade to crappy old html. XAML is infinitely superior. You can't even extend HTML server-side without writing code :( It's got loads of odd rules. It still thinks everything is an overflowable document when I want to write an application.
The web just jumped back to a kooky little language that's not grown for decades. Javashit.
Silverlight had support for static, dynamic and even functional languages! C#, VB.Net, IronPython, F#. And it's actually fast and compilable unlike javaslow.
(p.s. I don't actually mind javascript that much, but I do think it's pretty poor compared to C#, Python, Ruby, etc. I do actually detest html though.)
A lot of us don't need cross device compatibility. In fact cross device compatibility is pure laziness in many instances as a iPhone optimized web app should look very different to a laptop/desktop browser optimized app.
I'm not really sure where I stand in all this, but I'm not dancing around with joy about HTML5, which I think is pretty basic and ridiculously behind the times. These are features they should have introduced a decade ago.
I also really wish they'd make some way I could use other programming languages in the browsers.
As far as HTML / javascript goes, I'm beginning to get the impression that you don't like it. I understand, I actually hated touching javascript until I fell into JQuery. Even with it, I think developing javascript feels half-assed. But that's what the platform uses and modern browsers are generally fast enough. I tend to think of HTML as basically a display protocol though. It's ugly, but it works.
Take heart though, you can write the server side in whatever language you want, and your server-side can write your javascript for you.
It feels as if the same people who talk about beating 'proprietary' with an open web, open standards and open source code seem to miss we have _no_ choice when it comes to web programming, it's html/javascript or bust.
And javascript is not fast enough. Not even vaguely close to being fast enough. You must have seen the semi-regular 'look what I did with HTML5' demos, yeah great, until you put them next to a flash or silverlight demo. Then suddenly it looks pathetic. It's not up to the job.
This is a step back, not a step forward. It's not for the 'greater good', html needs decent competition to keep it modern. Competition is healthy!
While it would never happen and will never happen, Microsoft releasing Silverlight as an update to Windows could have given the HTML standards the kick up the ass they need to start taking application development seriously.
For most of us the browser is the new defacto OS.
We're a community of entrepreneurs and developers for pete's sake. And yet we're cheering on a virtual quango creating HTML5.
Relying on committees to drive forward the web is absurd. When did meetings and committees ever actually solve a problem or produce amazing innovation?