Microsoft might as well just stop making a home version of Outlook at this point, because with Google, Yahoo, and Microsoft all competing with each other for the webmail service, the only thing Outlook is useful for anymore is internal corporate messaging and scheduling. As webmail increases storage space, more and more people will move towards it, and that will be the end of local mail storage. I see that as a positive change, considering how often people lose their data, and how important many e-mails are. Its actually sort of sad that we've just become accustomed to e-mail not being available after 2-3 years...
Mozilla has basically admitted as much by dropping Thunderbird from its core responsibilities.