What we really need is a good way to execute desktop apps as if they were web services: accessible from nearly any device, access to your data with minimal complication wherever you happen to sign in from, and a lightweight, instant-response, zero-install interaction model. If we value "native clients", we need to address the things that make web clients more convenient.
> What we really need is a good way to execute desktop apps as if they were web services
I think the closest thing we have is the remote desktop protocol. I have used Thunderbird on my desktop via the rdp client I have installed on my phone (though with some degree of difficulty due to the interface and input limitations).
I think something like that could work if rdp clients provided a better interface for clients not using a desktop computer.