Lucifer - do you think that you are in some way superior to the rest of us?
I don't think there was anything wrong with the original question - it makes a perfectly valid point & I speak as an aviation consultant with over a decade's experience in market forecasting and airline economics. If it is ok for me what makes you so special? (But then if all you do is fly Tridents in FS2004 I'm not surprised)
To the original poster, the 777-400 would be a great replacement for the 747-400 if engine-power and structural issues do not get in the way. For example, could the landing gear take the additional weight; would an even longer stretch cause problems with tails scrapes etc - these are questions I could not answer but from an economics point of view you would get a considerable seat-mile cost advantage over the 747.
Going to 4 engines would not be a go-er as the whole airframe would have to be redesigned which would be very expensive and it would not be any different to the 747.
I suspect a further stretched 777 will not happen as Boeing do not want, at this stage, to create a competitor to the 747.
Hope this helps.