Speed is a technical problem, which may get attention, if it becomes really the problem. The rest are not even near the problems.

In my view Python's main advantage is it's sweet spot in the zone, being neither too "mathy" (in the sense of syntax), nor too low-level or syntactically verbose.

My believe is that there probably will not be a successor to Python as we know it.

Most likely, programming world will undergo some kind of paradigm shift, which will make all programming languages equal. Something a kin to zero-coding or brain-computer interfaces, but the reality will be even more interesting and not exactly predictable. Maybe, Open Source / commons will become so advanced, that software reuse will make wonders, seamlessly linking proven ontologies with the new software... In math-heavy software, proof systems may provide a way to build software solutions in the provable way (have you seen for example how a function implementation can be made in Idris 2 semi-automatically?). Dots will be connected, programming will become even more joyful, because programmers will need to solve genuinely new problems, not just remix old tunes.

In Python, one can program at the speed of their thought. One way to overcome that is to make something marginally better UX-wise (hardly), but most probably only big paradigm shift I tried to contemplate about above will make it RIP.