@Bass:And yet HTML has spectacularly failed to gain much traction when it comes to mobile apps. Apple insisted on it for the v1 iPhone and nobody cared about iPhone development till something better came along, webOS and ChromeOS pretty much tanked at launch because there just wasn't any drive for HTML based apps. Android, iPhone and even WP7 have all had way more take up by providing a more native-like development environment.
'Web applications' like C9 are really a different kettle of fish, they have a place but rarely seem to be a user's preferred choice given the option. And developers in general will prefer to stick to the tools they already know, it's not like they gain anything by going down the HTML route. As you say, time will tell, but I don't expect to see every developer suddenly jump on the HTML bandwagon just because they now can.