Boeing says the upgrade could be available on line production aircraft as early as 2015 and also available as a retrofit at some point on Block II aircraft.
That time frame along with F-35 uncertainty probably means no one knows the answer but possibilities, like the ones you raised, are being considered.
FYI for those who want to see the proposed upgrades, we produced a video and some pics back in Feb at Bangalore.
Video:
http://www.flightglobal.com/articles...t-options.html
Pics:
http://www.flightglobal.com/blogs/as...boeings-a.html