Two wrestlers have already been selected for the match but there's more to be added.
On Raw, Kurt Angle came to the ring to make an announcement about Brock Lesnar's next WWE Universal Championship defense. Roman Reigns interrupted to assert that he should have became Champion at the Greatest Royal Rumble event and wants another shot at Lesnar. Before Angle could continue his announcement Bobby Lashley joined the two men in the ring and said Reigns should step aside because Reigns has had his chances before.
Angle finally got to his announcement that there will be a multi-person match at the Extreme Rules pay-per-view which will determine the next challenger for Lesnar and coincidentally Lashley and Reigns are two of the participants.
Angle did not name any other wrestlers for the match and did not say how many wrestlers would be in the match but it will be more than Reigns and Lashley.