I doubt they will derate the NK-32 down to 23 tons thrust when it currently generates 25 tons of thrust...
Why ? Pak-da according to the article is twice as light as tu-160. Being subsonic, no need lot of power to reach more than mach 1, the main issue is to make it able to fly 15 000km as wanted so reducing power increase range.
I've never heard of anyone ever making a new generation of engines for strategic aircraft intentionally weaker than previous generation. If anything their making a high by-pass version of NK-32, which means their trading high exhaust speed for pure thrust. You don't seem to know what your talking about, intentionally making the NK-32 high-bypass means greater payload capacity and range (at the expense of supersonic speed), it will likely have thrust greater than 25 tons not less. Besides the 15,000 km range has already been achieved by the Tu-95 series, if anything it has to be exceeded because the PAK-DA will likely have the advantage of a blended wing-body design, the use of winglets, the use of 3D-printed composite materials and shape memory alloys, the use of Continuous Climb and Descent Operations, a modernized Flexible Navigation System, as well as placing the engines above the chassis near the vertical tail (both to reduce drag and RCS).
The advantages of a blended wing body (BWB):
The advantages of winglets:
The advantages of 3D shape memory alloys:
The advantages of Continuous Climb and Descent Operations:
The advantages of a Flexible Navigation System:
The advantages of engines above the chassis near the vertical tail: