Regarding single-line only lambdas, I think that isn't an intractable issue with the grammar.

Guido van Rossum basically said parsing them is hard, and he doesn't like lambdas in the first place, so it won't happen. [0]

Similar to "tail call optimization encourages dirty FP nerds" logic. Terrible decisions IMHO.

[0]: https://www.artima.com/weblogs/viewpost.jsp?thread=147358