On the one hand, the US was ready for integration. The Civil Rights Act, which outlawed segregation in public facilities, was passed by Congress in 1964. The passage of the law caused no huge protests or resistance. Professional sports leagues all had African American players. These things showed that Americans were at least somewhat ready for integration.
However, there were ways in which Americans were still not ready for integration. Some Southern colleges still did not have have African American football or basketball players. Integration of schools continued to go slowly and, in the North, there would be fierce resistance to busing to integrate schools even into the 1970s.
So, it is hard to say that all Americans were or were not ready. American attitudes towards integration varied from place to place and depending on what institutions were being integrated.