The names mentioned are Lorenzo Sotomayor, Albert Selimov, Abdulkadir Abdullayev and Magomedrasul Majidov.
Those who watched the Olympics will remember that Sotomayor, originally from Cuba, won the Olympic Silver medal, and was one of the most talented boxers at the games with a style that would take him far in the professional ranks. The 31 year old was maybe a bit on the old side to have continued success but had proven his desire to fight by leaving Havana and actually beat Cuba's Yasniel Toledo in the quarter final.
Albert Selimov is best known for defeating Vasyl Lomachneko but is also 3-time World Amateur Champion medal winner, claiming a gold a bronze and a silver. He also claimed a Gold at the 2008 World Cup and is a 2-time European champion. Although 30 years old he was still considered a great fighter and had links to the boxing cultures in both Russia and Azerbaijan, suggesting he could have turned professional and headed to Moscow for a potential big money and fast tracked career.
Abdullayev is a former World Amateur Championships bronze medal winner and a former European champion. Aged 28 there was plenty of time for for Abdullayev to continue to mark a mark on the sport going forward, ans he'd only be 32 when the Tokyo comes around. He also managed to gain valuable WSB experience and seemed ready to turn professional the "traditional" route.
Sadly the biggest loss to boxing is big puncher Super Heavyweight tough guy Majidov. The 29 year old is a former Olympic bronze medal winner, a 2-time World Amateur champion and a European Amateur champion who has competed in the WSB and been one of their stars. He holds notable wins over the likes of Erislandy Savon, Anthony Joshua, Roberto Cammarelle, Ivan Dychko and Magomed Omarov and would be a huge addition had he decided to become a fully fledged.
The source suggests that the 4 men will not be turning professional but will instead look for other work inside Azerbaijan. A really disappointing bit of news for fight fans and those hoping to see a wave of Azeri's fighting on the world stage as professional.