I also would like to drop backwards compatibility in favor for a clean simple language, because I happen to write completely new functionality.
If you ask yourself the question: "Do I want to break backwards compatibility in 2020?", then that same question could have been asked in 2003. Which would mean that the language lost traction (at least that is my opinion), because I could not recompile my old code and therefore I keep using the old before C++2003 compiler. So, the reason that it is popular, _is_ because it takes care of installed base and does not break existing code (or at least minimizes breakage).
There have been plenty of from-scratch languages that are designed as a better C++. Many have died, of those left no one has yet gained significant traction [1].
It is not clear why yet another an incompatible language would be better just because it happens to be called C++. The effort would be better spent on improving one of the existing alternatives.
[1] Plenty of newer languages have had breakaway success, but no language that is meant to be a full C++ replacement has yet. D has passed peak hype without a breakout. Rust might still make it, we will see.
