Very good. Your not unique.
Can you think of any similar situation where people have pulled weight from a mature design? Offer us an example of where this has worked in the past?
Airbus are always looking on weight savings. About 10 years ago, I was working on fuel systems R&T for single aisles, looking at different pumps, galleries and venting (flame arrestors). Some of it went for evaluation onto production aircraft, others got shelved for the next gen single aisle and yet more got parked as not suitable. There is no real song and dance about it as its seen more as routine work.
Here is one of the few instances where it made headlines - and as far as I know its now on in-service aircraft:http://www.airbus.com/newsroom/news/en/ ... nting.html
30kg in one simple sub-assembly.
They saved about 50kg on the A320 by updating the cockpit from CRT to LCD.
Its not tonnes, unless there was a serious focus and a wrapping up of multiple improvements, it never would be. Also, given the focus largely seems to be on improving range, then they often aren't looking to take structural weight out, but rather load it more.
Also, most 25 year old aircraft designs are nearing EOL, not getting major revamps and money spent on them!