Some types of apps might work okay as a mobile web app (Facebook comes to mind), but there are definitely many native apps that simply aren't feasible to do in HTML5.
Can you imagine Word Lens being implemented as a web app? Yeah, I didn't think so.
Native apps haven't been in demand on the desktop for a while, and smartphones are getting faster all the time. It seems that will be dual core, 1 GHz this year. How long before performance becomes a non-issue?
Quad core is inevitable, it's just a question of when. They say 2012 for the chips in that article; but not when for devices using it. Dual core devices are scheduled early this year.
They also mention 2.5GHz - the big issue is power usage. I guess you you can turn off 3, and underclock when not needed.
This topic is very popular amongst hackers lately. I find the web developers in particular resist the native app trend, to avoid Objective-C (iOS) and Java (Android). Typical web developer lives in Javascript and a chosen high level language (Ruby, Python) on the server side.