This video talk about using new light weight matterials to reduce weight of Russian engines. Interesting it is talk the materials will.also be use for PS-90a and not just new gen engines like PD-8, PD-14 and PD-35. Shown eventough it is older design engine, but Russia will continue retain that engine.
In my opinion it is not matter PS-90a already proven, but also there will be limited production capacity for new gen engines. Shown Il-76-90a, Il-96-400M, Tu-214M continue will be mainstay for both Russia military and commercial needs for at least until end of this to early next decade. All before enough capacities being build for new gen engines and planes.