Even after JFK's initiated reforms, quotas based on origins (birth county of future immigrants or birth country of existing immigrants in the US) is intact. If one sees this as a formula based on origins, some variables are changed after Immigration and Naturalization Act of 1965. So, it is very hard to get rid of origin and quota-based formulas. Now Trump wants to change some variables.

How long before the reintroduction of segregation?

That does seem a natural extrapolation of this.