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The Guys over at Hackaday started a open source community project to build some USB hardware with a smart card and a touch display for password managment. As a KeePass user I think this would add some more security and portability. This just started and there is still time to give your input and feature requests. I would welcome to have KeePass as a host application to mange this new device. I guess it would me more secure to use the touch screen to enter the master password and not store the database on the PC.
All the functionality you mentioned is possible via a plugin. Plugins can export databases (by implementing a FileFormatProvider, which sends the data to the smartcard). And plugins can implement key providers  to decrypt/open database files (one example is the LoginCard Key Provider ). Even a plugin could be written that directly 'opens' a database file for editing from the smartcard, if the smartcard supports accessing all data in some way. So, multiple types of integration are possible.
Personally I think such an optional integration would be a great idea. I'm not a smartcard expert and cannot help with the communication between the smartcard and the plugin; but if anyone has questions developing a KeePass plugin (all except the smartcard communication), I'll gladly help.