Reengine, upgrade to fly-by-wire and glass cockpit would you think this would be an valuable and viable option in the medium term long range market?
rb,
How may people have to tell you-NO!!!!
What you are proposing (particularly the Fly-By-Wire bit) would be an entirerly new aircraft, new certification, new manufacturing.
MUCH better to star with a clean sheet.
Aircraft design has moved on- do the same!!