10 years is far too pessimistic for this being a routine task, I think 2 years max. As you mentioned, you can already do this today by just giving GPT 5.5/Opus 4.8 an IDA/Ghidra tooling (a CLI or MCP, I have a custom CLI for it). You can start with the LLM going from the string anchors and renaming functions/globals, then when you have enough functions, the LLM can start working on typing - IDA has a very powerful typing API for HexRays-decompiled code, you can even type locals and it all persists in a DB.

My custom IDA CLI is just a simple thing on top of IDA Python's integration + ida-domain + some higher-level helpers, and works as a daemon with workers, so a stale/bad request doesn't corrupt an IDA DB (an issue I had when I was using idasql).

A bit offtopic, but: do you have any links to your efforts? I'm curious to see what other people do in this area.