Maybe someone else has posted this earlier but I believe the 777 that DAL purchased came from a leasing company that had the aircraft on lease to Malaysian Airlines. It will be parted out.
While technically possible the GE/Trent conversion would be impractical. The last time I saw that done was to a Saudi MD11 that went from GE to P&W and I have since heard it went back to GE's. Go figure that one out.
Keep in mind that just about anything is possible if you throw enough money at the project. Does not mean that its smart, wise or prudent. I doubt that Boeing would ever get behind a sex change like that and would simply withhold engineering and performance data needed to certify the project.