China appears to be accelerating development of a super-heavy lift rocket

That's the first I have heard of SLS being ready as early as 2021. I wonder, when it comes online will NASA stop using SpaceX & ULA for space station supply/people missions?

I find it interesting how rocket development speed seems to have slowed down. It took the US a little more than 10 years to go from barely being able to launch any rocket to the Saturn V. With all the experience we have now it still takes more than 10 years to develop a new heavy lift rocket. Considering that usually everything is late this rocket will probably fly after 2030.