I would like to get some reality testing here. Mobile apps are great. They reside in people's pockets. You can communicate by sending notifications. If you have an app that is downloaded and installed 100,000 times you can send notifications to 100,000 users. Is this the beginning of the end of email lists???
While it might sound a bit odd, nothing is wrong with boosting your ongoing marketing efforts by adding a subscription form to your mobile app itself. You could collect email addresses from early adopters to inform them of updates. Or perhaps you’re planning a really great newsletter for your audience and feel that in-app sign-ups would give the app a real boost.