I don't think we will ever reach the same accuracy simply because some languages are harder than others. Writing correct C (not just "working C") is difficult because of the number of footguns and the amount of reasoning and implicit state tracking you have to do in your head. LLMs are not free from this, if anything that's harder for them. Meanwhile languages like Java are more difficult just because they are verbose and spread information over many files. Languages that are explicit, not overly verbose and make it difficult to make subtle mistakes will always have the advantage with LLMs
I more bullish on the Python -> Rust pipeline. The two languages have a lot of overlap in philosophies, have great interop, and have similar levels of guard rails (when it comes to multithreading Rust even beats Python in terms of safety). And both languages seem well suited to being vibecoded
If not then I see the argument for everything being done in Python and performance coming from optimizing Python -> C.