The world’s jetliner fleet should top 39,500 aircraft in 10 years, as a wave of new deliveries­—overwhelmingly narrowbody twins—combines with a somewhat slower retirement rate to expand the in-service fleet by an annual rate of about 3%, according to Aviation Week’s latest Fleet & MRO Forecast.

The 2014 forecast predicts that more aircraft will be in service by 2023 than had been projected in last year’s forecast, and those aircraft will fly more, with utilization projected to increase by 4%. Retirements will slow as overall fleet age falls, and deliveries will continue at a torrid pace until around 2018 as the so-called “bow wave” of replacements subsides in favor of a more natural growth and replacement cycle.

Deliveries during the 10-year forecast period through 2023 are expected to reach just a shade more than 17,000 aircraft, while the forecast projects that some 7,500 aircraft will retire during that period.

Even though this trend still represents a relatively high retirement rate and reflects retirements at somewhat younger ages than has been historically true, it is revised downward from last year’s forecast by about 5%. The projection continues to assume that more aircraft will go straight to part-out than did in the past, and at younger ages, at least in the medium-term.

The Asia-Pacific region and China will account for the largest share of deliveries, a projected 5,800-plus aircraft—90% more than in Western Europe, which should see just over 3,000 new aircraft delivered during the forecast period.

The new-generation narrowbodies—the Airbus A320neo series and the Boeing 737 MAX family—will overtake today’s A320 and Boeing 737NG families in the middle of the decade, when they become the fastest-growing fleet types in nearly every region of the world.

The Aviation Week Intelligence Network’s fleet and forecast team expects to see Airbus make serious inroads in the Asian market, and while typically Boeing-heavy countries in the region will probably remain Boeing-heavy through the decade, the forecast shows Airbus edging out Boeing in total Asia-Pacific region and China market share by 2023.

While MAXes and NEOs dominate the delivery forecast, they dominate less in the Asia region than in other parts of the world, in part because this area is in the backyard of some of the stronger challengers to the traditional Airbus-Boeing duopoly. Not surprisingly, Comac enjoys a higher market share here than in other regions—Aviation Week sees the ARJ21 delivering 237 units into the region during the forecast period. Coming in just outside the top 10 Asian deliveries, in 11th place, is the C919, expected to deliver 215 units in the region during the period.

This is good enough to give Comac an overall 8% share of the Asia and China deliveries market, but the manufacturer still faces a serious headwind from the duopoly of Airbus and Boeing. The A320neo alone will account for 11% of deliveries, and the MAX takes up 12%. Even the turboprop ATR 72 by itself will come close to Comac’s market share, at 7%.

Another phenomenon animating the latter years of this forecast period is the emerging dominance of super-long-range twins, which the Aviation Week analysis team believes will eventually spell the end of the four-engined commercial transport.

A look at today’s order book is revealing. Airbus has more than 700 orders for the efficient and long-range A350 and Boeing has about 950 orders for the 787, with similar advantages. That is a total of 1,650 very efficient medium-sized jets that will all be delivered during the next eight to 10 years or so. Next, take Boeing’s 777-9X into consideration; deliveries of this airplane are likely to begin around 2020, adding to the pressure on the four-engined aircraft.

By the end of Aviation Week’s forecast period, the world will be awash in very-long-range twins, tremendously efficient aircraft capable of unrefueled flights of some 8,000 nm. or better. The A350 with the longest legs—the -800—will go 8,400 nm, and the 787-9 reaches 8,500 nm. The 777-9X, too, will be an 8,000-nm.-class airplane, and, carrying a lighter load, the -8X should reach 9,480 nm. With ranges like this becoming commonplace, and at twin-engine fuel and parts efficiency, the case for hubs begins to ebb. Hubs will always exist because they serve an important function, but the percentage of travel through hubs will continue to drop as more and more point-to-point routes are developed.