Football's rule-making body IFAB has given the go-ahead for trials of additional 'concussion subs' with the pilot studies able to begin as early as January.
The body also gave the green light to the further extension of the temporary measure for five subs per game rather than three - brought in due to the COVID-19 related fixture congestion.
FIFA has said it is ready to trail the concussion sub system in next year's Olympic Games while the Premier League is reported by British media to be eager to introduce the system as soon as possible.
The system would be for permanent substitutions of players with suspected concussion even if their team have used all their substitutes already.
However, the changes do not make provision for 'temporary concussion substitutes' which some in the game had been calling for as a way for players to have more time to be checked out before returning to play.
IFAB said they had consulted with medical concussion experts, team doctors, player representatives, coaches, competition organisers, refereeing and laws of the game experts.
The extension applies for domestic competitions ending by December 31, 2021 and for international competitions ending by July 31, 2022.