Airbus isn't ignoring it, hence the A321NEO concept - whether or not they sell enough to actually bring the plane to market is another story, especially given the A380 project has descended into a disaster with the airplane missing all kinds of sales targets now the initial hype is long over.

My personal opinion - neither aircraft should really be on the drawing board especially with the flexibility the 787 offers in the smaller variant with incrementally more seats than the 757-300 and vastly more flexibility...but for some reason US airlines just don't like flying widebodies on dedicated domestic routes anymore.

Back in the day (ie late 90s, early 2000s) I often flew the PMCO DC10 from IAH to LAX and SFO and LAX to HNL, not to mention the DL L1011 and later the 763 from FLL to ATL.

But if airlines continue this silly disease of widebodyitis and want to order a new 757 in sufficient numbers to make a case to Boeing, then the right move is the 753 fuselage in carbon fiber material mated to 787-style wings and updated systems. If there is minimal demand, but just enough to make it worthwhile to incrementally update the 753, then redo it as-is with new engines and the sky interior and call it a day.

I think in the end, it will also come down to Airbus actually producing the 321NEO or not before Boeing decides on a competitive response.