How Could Informed Delivery Change Mail Over Time?

What does Informed Delivery from the USPS mean for the long-term future of direct mail? It certainly offers some intriguing possibilities.
Informed Delivery is a new service from the USPS that takes the scans used in postal automation and provides them as a service to postal customers. Once participants sign up, they receive a daily email that includes images of the first 10 pieces of mail they will be receiving that day. If there are more than 10 pieces of mail, they can click on a link to see the remaining images.

Already, more than 2 million people have signed up for Informed Delivery, and 90% of those say they check their Informed Delivery email every day.
For marketers, this means that, whether postal customers are home or not, they still know what letters, postcards, invoices, or other mailers will be arriving in their mailbox that day. The email can also contain links to web pages, video, or other digital content, enabling the recipient to respond to mail even before they get home to receive it.
You have to give the USPS credit. Between its range of promotions for print-to-mobile technologies and innovative printing techniques and new services like this (and Informed Visibility, which is another post), it’s made substantial and laudatory efforts to make mail more valuable.
In this case, one of the questions raised in my mind is how Informed Delivery could change how mail is concepted and designed. Since these images are of the outside of the mail only, could this impact a marketer’s decision regarding mailing format? Certain formats provide more visibility than others. With postcards, for example, participants can read the entire message from the digital image they receive. Meanwhile, others (such as letters) provide little or no visibility at all . . . unless the mailer is using messaging on the outside of the envelope. With Informed Delivery, all the recipient knows is where the mailer is coming from.

Over time, could Informed Delivery impact the mix of mailing formats to favor those that provide more visibility of the message via the digital image? Could it drive more investment in on-envelope printing, as well as personalization on the outside of envelopes?
Informed Delivery certainly provides a lot of benefits to mailers, but to me, one of the most fascinating impacts on the mailing market is how it could affect the choice of mailing formats and the way marketers design their pieces. To what extent will mail begin to be designed with the images viewed through Informed Delivery in mind?
What do you think?