C++26 std::execution vs. Rust's async/rayon: Two different philosophies for the future of concurrency?

As C++26 nears, the new std::execution framework (P2300) is one of the most significant additions. It's a foundational, lazy, and composable "sender/receiver" model. The goal seems to be a "grand unifying theory" for asynchrony and parallelism—a single, low-level abstraction that can efficiently target everything from a thread pool to a GPU.

This is a fascinating contrast to Rust's approach, which feels more bifurcated and practical out-of-the-box:

1. For I/O: async/await built on top of runtimes like tokio.
2. For Data Parallelism: rayon, with its famously simple .par_iter().

Both C++ and Rust are obviously at the pinnacle of performance, but their philosophies seem to be diverging. C++ is building a complex, foundational abstraction (sender/receiver) that all other concurrency can be built upon. Rust has provided specialized, "fearless" tools for the two most common concurrency domains.

For those of you working in high-performance computing, which philosophical bet do you think is the right one for the next decade?

Is C++'s "one abstraction to rule them all" the correct long-term play for heterogeneous systems? Or is Rust's specialized, "safe and practical" toolkit the more productive path forward?