New narrowbodies dominate at Paris this year, as Airbus and Boeing face continue weakness in demand for their “Show”ier widebody jets.

As civil aircraft manufacturers gather for this year’s Paris Air Show, they are receiving mixed demand signals from the market. In spite of the massive drop in new order activity for both Airbus and Boeing since last year, backlogs are still more than healthy and production levels are expanding. IATA has been reporting better than expected traffic figures for the first few months of 2017, indicating that volumes remain resilient for now. But others warn the good times may soon be over.

Short-term growth is still likely, at least for the next 12 to 18 months, said Adam Pilarski, senior VP for Avitas, at the recent ISTAT Asia conference in Hong Kong. But he and other experts in predicted that the peak of the cycle is nigh. Pilarski believes that “long-term problems are mounting and the bubble is expanding.”

“I’m moving away from assuming the bubble will start slowly deflating, to a higher probability of it bursting,” he says

Laurent Delvart, head of Asian aviation for Credit Agricole, noted that a downturn will come. “I’m not a believer in [the theory] that this time will be different,” he said.

The industry achieved “extremely good results” last year, said Delvart. And while it is not necessarily the start of a broader slide, numbers have generally been down in the first quarter of this year. Fuel prices have “not gone up dramatically,” but yields have been lower due to extra capacity coming into the market.

For Boeing, the 2017 Paris air show is a key opportunity to showcase the 737 MAX at a critical time for the program. The company is tipped to use the event to officially launch the 737-10, its long-debated counter to the A321neo and the fourth major derivative of the family. It will also highlight progress on the 737-9, which entered flight test in April, as well as mark the start of MAX deliveries which began with the handover of the first 737-8 to Malindo Air on May 16.

Having enjoyed a relatively hurdle-free development path for the MAX, the late drama associated with the discovery in early May of a potential forging flaw in some of the aircraft’s CFM Leap-1B engines came as an unwelcome interruption. Although Boeing and CFM were able to re-shuffle engines to resume customer acceptance flights and deliver the first aircraft a mere 24 hrs. later than its lately revised schedule, the aircraft manufacturer is still dealing with the downstream issues. These include an inevitable slow down on pre-delivery 737-8 production and customer flights, as well as flight testing of the 737-9.

The first 737-9, which had just completed initial airworthiness testing when flying was stopped in early May, was about to begin flutter checks and had not resumed flight tests as of May 17. Fortunately Boeing says the 737-9 test program, like that of the 737-8, was ahead of schedule, providing some margin. Boeing remains confident of catching up quickly, however, and expects to begin 737-8 deliveries to Norwegian and Southwest in July and September, respectively.

Progress on sales of the 737-10 will also be a talking point. Approved by the Boeing board late last year for offer to airlines, Boeing has had at least seven solid months in which to accrue sufficient orders for a firm launch at the show. The company revealed more about its 737-10 campaign in March at the ISTAT Americas conference in San Diego.

Airbus, meanwhile, enjoys a comfortable market share vis-à-vis the 737 MAX and is in little hurry to make additional moves.

That said, Airbus is studying options a composite wing for narrowbody aircraft, a path the company has so far avoided because it was not convinced of the benefits. The proposed 797 could be the catalyst for change, particularly if the combination of an existing, adapted airframe with that new wing and new engines would allow Airbus to avoid having to invest in an all-new aircraft for the category.

In order to compete with the NMA, Airbus would have to stretch the A321neo further. The aircraft, in its highest density lay-out, can currently accommodate around 240 passengers, but that version would not be capable of flying transatlantic distances. The A321LR, the long-range version of the family, is currently planned for a maximum range of 4,000 nm and Airbus has been looking for ways to extend that range by a few hundred miles.