Google's Google Groups is also the most popular interface to USENet, do people ever bother to install a superior reader? People still use Hotmail and Yahoo mail even though POP3 and IMAP interfaces are freely available, and desktop clients offer better interfaces. How many people are making a living from chat clients? Torrent clients?

You will find that people hardly seek out superior ways to do the usual everyday things, unless prompted by a friend or mass public hysteria about a new possibility. News reading is not the sort of activity that encourages viral behavior; it's a solitary activity and the reading tool in-use can not compete with the ever changing content for attention (except in format and protocol changes, when the tool that supports the widest range of formats becomes popular.)

Your best hope, if you build it, is to be ready to launch something "blackhat" and subversive, if and when a major online paper goes paywall. But once you do that, you're entering unmonetizable territory.