Microsoft: Half of Exchange inboxes to be Microsoft-hosted in five years

While all the interest Microsoft's potential "transaction" with Yahoo is getting, it's easy to forget that online advertising isn't Microsoft's only strategy for monetizing its current and future Web-centric services.

While all the interest Microsoft's potential "transaction" with Yahoo  is getting, it's easy to forget that online advertising isn't Microsoft's only strategy for monetizing its current and future Web-centric services.

Subscription licenses also are going to be a big piece of Microsoft's cloud-monetization puzzle. Microsoft already is selling Microsoft-hosted versions of Exchange and SharePoint to large enterprises. In March, it started beta testing Microsoft-hosted versions of Exchange, SharePoint and Office Communications Server that will be sold to smaller companies, as well. The new subscription plans for those Microsoft-hosted offerings should be on the price list some time in the latter half of this year.

Microsoft seems pretty confident that its customers are going to stay in the fold by moving from on-premise Microsoft business apps to Microsoft-hosted versions of the same. From a recent Reuters story:

"In five years, 50 percent of our Exchange mailboxes will be Exchange Online," said (Microsoft Senior Vice President Chris) Capossela, who expects a portion of Exchange Online customers to come from customers switching from International Business Machines' Lotus Domino system."

What's your take? Is Capossela's projection overly ambitious? Too conservative (in that it shouldn't take five years for this move to happen)? Or does it sound on the money, to you?