Something to consider in this connection is that the Soviet/Russian submarine design bureau system is quite different to what we have in the West. In the United States, for example, NAVSEA has a few naval architects who design submarines, as do the major shipyards (Electric Boat and Newport News). But these are small groups of people, at most a few dozen people each. These groups do conduct concept design studies, but typically they are classified. Because of the very strict restrictions on releasing anything even tangentially-related to naval nuclear propulsion, these concept designs rarely enter the public sphere.
In Russia, the system is different in two key ways. The major design bureaus (Malakhit and Rubin) have orders of magnitude more naval architects. During the Soviet era, I recall Rubin had several thousand, although I am not sure how big the design bureaus are these days. The design bureaus, on their own initiative as well as in response to the Navy's requirements, produce a huge number of concept designs. And the Russians have a much more lax attitude toward secrecy, at least when it comes to older submarine designs. So not only were there more concept designs, knowledge of their existence is usually not classified.
All of this is a long way of saying that I would not look at something like Project 958 too critically as something that the Soviets planned or even wanted to build. The fact that it received a project number suggests that there was some interest by the Navy, but the design bureaus made many such unrealized designs. So I wouldn't say that Project 958 not being built has anything at all to do with Project 885 unless one can find specific evidence of that. Project 958 dates from the late 1960s and early 1970s and seems to have been somewhat related to the early stages of the Project 971 (Akula) design. Project 885 began to materialize about a decade later.