I would love also to see support for Yubikey token devices, especially since as Apple opened the NFC interface to allow apps to read. And Yubico also provides a SDK for dealing with it on iOS. With that the suggestion that not all mobile plattforms are supported (probably cause of iOS) does fall in my eyes, since majority devices does feature NFC or a USB port, making it useful for probably over 90% of the Enpass users. What I have in mind for the use would be the choice of a dual auth (so you can use your passphase OR the token) or a combined auth (user passphase and a token from the yubikey). The dual auth variation would be nice for my parents, since we had it already that they forgot the passphase and we had to redo all... thank god it was at the beginning and still easy to readd everything.
Besides not all Macs come with a TouchID, so this could give us the same benefit as the TouchID fellows. Also I wouldnt mind it being a premium feature, I mean after all its work and that needs to be rewarded.