Just off the top of my head, it would be nice to remove std::initializer_list from the standard to make uniform initialization truly uniform, and to remove to t

Just off the top of my head, it would be nice to remove std::initializer_list from the standard to make uniform initialization truly uniform, and to remove to the 'explicit' keyword to make it the default behaviour. There's also stuff from C that can be surprisingly complicated, like integer promotion rules, but if you change that sort of thing you might as well design a new language from scratch.