Bertie the Bunyip wrote
The next generation are eschewing bleed air driven pressurisation
and going to seperate supercharger systems. A lot of older turboprops
used this system as well as a small number of jets. The 787 will have
this system.

The B-707 had both Bleed Air and Turbochargers. We used the Turbochargers
most of the time. An engine bleed line spun a turbine which then turned
a fresh outside air compressor.

Bob Moore
17 years in B-707s