Equality of opportunity means we aim to provide everyone access to the same chances. Reduce the (present and historic) systemic discrimination by race and gender. Improve access to the basic tools required to achieve success (education and mobility). But we cannot guarantee that everyone will turn out the same (either by choice, fortune, or misfortune it just won't happen). It may still be a pipe dream, but it's far more achievable.
How will you do this and how will you measure the results of the attempts to do this without measuring the outcomes of your attempts to do this?
The thing is, we know that they're not. And since skill and preference are not equally distributed, equality of opportunity will inevitably lead to inequality of outcomes. And that's okay: different people are different.