Previously successful aircraft, now flops

[Cautious Optimist]

Hi

I've always wondered why aircraft that sold well (or well enough) in their previous generation, have completely flopped in their current incarnations, such as:

Airbus A319-100 1,486 vs 73 Airbus A319-100N
Airbus A330-200 664 vs 11 Airbus A330-800
Boeing 737-500 389 vs 69 Boeing 737-600
Boeing 737-700 1,128 vs 286 Boeing 737-7MAX (a bit better than I thought! But still...)
Embraer 175 848 (the best seller!!) vs ZERO Embraer 175 E2 (!!)

Then there's the turboprops...ATR the only game in town and offer nothing in the vital 20-30 seat segment?! Where's the Saab 340NG, Jetstream 32/41 NG etc? Why hasn't Dreamliner/NEO innovations trickled down to turboprop level?!

I suspect the answer will be "economies of scale", but this would have applied in the 90s/00s and seemingly didn't, so I don't buy it! Also if it was due to this, why can't the manufacturers see it when launching the aircraft?!

On a separate note, I notice the A330-900 has 260-300 seats in a 3-class config or 460 max, whereas an A350-900 has 315 in 2-class, or 440 max - seems to me Airbus are competing against themselves?!

[DIBO]

For the A319, you'll have to add the A220 into the equation
Airbus A319-100 1,486 vs 73 Airbus A319-100N + 658 A220-300

[terrain safe]

Or the Boeing 747. They built 694 747-400 and only 155 747-800.

[PAXboy]

Times change. The markets change.
Airlines have spent the last 50+ years trying to plot where the market would be in 5 and 10 years.

Each time there is a recession, the market turns quickly and recovers slowly.

Manufacturers merge, get taken over and they phase out models they think will not make enough money to cover the cost of the take over.

Then airlines merge and go bust, leaving surplus frames.

There are so many variables that an upgraded version cannot be guaranteed a market. The 747-800 arrived as twins were proving their worth for long haul. The Hub and Spoke era arrived and has now mostly gone. Regional jets came on the scene. The list of reasons is very long