Emirates Airline wants Boeing to make a quick decision on the next-generation Boeing 777, with President Tim Clark claiming that the airframer could “sell immediately 150-200” of them.

Clark, speaking to Aviation Week on the sidelines of the International Air Transport Association’s annual general meeting this week in Beijing, says the initial client base also could include Qatar Airways, Etihad Airways, Japan Airlines, British Airways and American Airlines. Emirates alone has 174 Boeing 777-300ERs in its fleet or on order and will start to retire them in 2017.

Boeing has not committed to a new-generation 777 launch, and Air Lease Corp.’s CEO Steve Udvar-Hazy says he does not expect the manufacturer will “rush with the 777,” maybe leaving the launch decision until a year from now, so it can focus on launching the 787-10, which he sees as an “easier step technologically.”

But Emirates has other priorities. Clark says Boeing would make a mistake if it waited until the performance of the competing A350-1000 becomes clear. “If you think you don’t have to move because the -1000 is in trouble, think again,” he says, adding that “if you believe in your product and your client base is telling you the same, why wouldn’t you get on with the job and bag it?”

Udvar-Hazy tells Aviation Week that rather than a major overhaul of the 777, he would prefer the 777X program to add new engines, a new wing (although not an all-composite one) and a small stretch of around four frames.

ALC’s founder also says Boeing should not “become hostage” of a small number of airlines that want maximum range capabilities of the new aircraft that most other operators do not need. In his view, the solution to accommodate differing interests would be to offer one ultra-long-range version and a stretch that would offer a similar range as today’s 777-300ER.