In regards to the Epl, everything is still a little up in the air so nothing is really set in stone although it seems that it will be virtually impossible to sign any EU players under the age of 18 for say an academy due to Fifa regulations, which could hold English teams back as British talent are generally quite rubbish compared to young talents from other parts of the world. Not to add for players 18+ they must have played a certain percentage of games for their national team which varies depending on the country's Fifa coefficient.
Basically, smaller teams who are use to finding top bargains who turn to be top players, ala Kante, Mahrez etc. won't happen, whilst making it harder for the top teams in England to sign top talents as all the top English teams will be eager on getting the limited available talent, as "acknowledged" players are much harder to sign than say a player who is upcoming like Martial.