The improved fuel efficiency didn't play out - turns out that any improvements in engine cycle efficiency was minimal - to the point where the high pressure compressor is common between the bleedless GEnx-1B (787) and the conventional bleed GEnx-2B (747-8). The GEnx-1B simply incorporates blanking plates over the service bleed ports.
That's why you don't see bleedless engines on the 777X or the 737 MAX - it simply is not worth the trouble.
If the 777X and 737 MAX are fitted with bleedless engines, this will require a lot of changes at least:
The ECS (environmental control system) will change which may cause the change of AC bay----> this may cause the change the wing-body fairings
The APU will change: no bleed air for aircraft/engines
The wings anti-ice will change ----->change in the slats
The electrical system may change: VFSG's instead of IDG's
All these changes mean extra costs in addition the cost of certification of these new systems.
I don't know if it is
worth to fit bleedless engine in a new plane versus bleed air engine in new plane such B787 vs A350. But I don't think it is worth for derivative
planes such 737 MAX or 777X.
A summary of expected benefits of bleedless engines B787 according to Boeing:
A key benefit expected from the Boeing 787's no-bleed architecture is improved fuel consumption as a result of more efficient engine cycle and more efficient secondary power extraction, power transfer, and energy usage.Eliminating the maintenance-intensive bleed system is also expected to reduce airplane maintenance needs and improve airplane reliability because there are fewer components on the engine installation; there are no IDGs, pneumatic ducts, pre-coolers, valves, duct burst protection, and over-temperature protection; and there is no compressed air from the APU, resulting in a simplified and more reliable APU.The 787 no-bleed architecture also features modern power electronics and motors that will provide increased overall reliability, decreased costs, and improved performance. This is an extract from this article:
https://www.boeing.com/commercial/aeromagazine/articles/qtr_4_07/article_02_1.html