The most likely scenario is Bivol's rematch with Saul Alvarez (58-2-2, 39 KOs). The fight will take place in May in the USA. However, it is not a fact that by that time the Mexican will cope with his health problems.
If Canelo is unavailable, Bivol will have to cross gloves with former super middleweight champion Callum Smith (29-1, 21 KOs) or Joshua Buatsi (16-0, 13 KOs). These fights will take place in the UK or the United Arab Emirates.