I think it's a bit cute of Boeing to call the 744LR part of the 747X range. Realistically it is an add on to the existing 744 range. The design changes between 744 and 744LR are minor when compared with what is required to go to the full scale 747X. The 744LR differs little from today's extended range 744s used by QF and UA on routes such as MEL-LAX. Yes, there is some updating of avionics, more powerful engines and of course updated 777 style interior (am I the only one who thinks the much vaunted 777 interior is a very successful piece of industry hype but probably ultimately unnoticed by the travelling public? When I flew on 777 I can't say I was surrounded by people complimenting the design of the overhead locker.)
The 744LR is a step along the way to the 747X just as the 743 was a step along the way to the 744 but I feel that in years to come the 744LR will be seen as part of the 744 family not the 747X family just as the 743 is part of the 747 classic family.