Only time will tell, that's the thing with potential. The three of them look like potential world beaters, but right now in terms of where they could peak;
Sterling: 8/10
Sane: 9.5/10
Jesus 9/10
Sterling - Finishing will improve, maybe never world class finisher but his speed, skill, dribbling and incredible intelligence should see him reach ribery/di maria level, maybe better
Sane - incredible physique, speed and skill, good composure and finishing too. Bale/ronaldo level possible
Jesus - Potential to reach legendary status