Any historic discrimination cannot be eliminated by just having a level playing field.
A reverse discrimination is an absolute requirement. However, care must be taken to keep the marginalized people from becoming dependent on that reverse discrimination.
The idea of abolishing an implemented discrimination after a certain period (10/30/50 years) is not correct. It creates unnecessary and many a times counter productive dependent of the marginalized people.
One solution is to design from the get go a gradually diminishing reverse discrimination: one that abolishes itself in a certain period (10/30/50 years).