One of the benefits of the system of regional batei din under the auspices of the Rabbinical Council of America is that it provides future converts with the security that their conversions will be broadly accepted and will not be unnecessarily questioned in the future.
The current system should in no way affect the status of conversions performed prior to its inception.
All those who were converted properly in the past in accordance with the dictates of halacha should be aware that the status of their conversions is unchanged. If an individual is concerned that his or her conversion may not be recognized, he or she may contact the Beth Din of America for assistance.