iOS and (especially) Android are far more open for developers than the consoles 4J Studios develops for, so it's been a question left unanswered if custom skins would be allowed on Pocket Edition. Today Jens has answered the question, replying "We will try to offer both" to a user's question "If you're going to choose between these two, What would you choose? MCPE Skin Packs or Custom Skins?"
Custom skins could be implemented via Mojang Accounts perhaps, as you can already login to your Mojang account to access Pocket Realms. Custom Skin Packs could potentially be purchased from Mojang and be available on your device, or maybe purchased through the App Store/Play Store. Whichever way you put it, the future looks bright for Minecraft Pocket Edition.