According to Bethesda softworks, they will not be releasing the code to any of thier games. Ever. So we can pretty much kiss goodbye to ever seeing a port of arena or daggerfall to the 2x or its successors. I would dig up the source for this, but it's buried deep in the official forums and i just don't have the time nor inclination at the moment.
You would have much better luck porting BG1
You would have much better luck porting BG1