Sounds nuts - but hear me out.
Nick managed to run 1:42.95 last year while setting PRs @400 (47.45) and 1500 (3:36). With those three times - it looks like he runs that fast fast 800 not with his relatively modest aerobic talents, but instead with an incredible amount of anaerobic endurance.
Ngeny had an 800m PR of only 1:44.29 - though a very very fast 1500m time of 3:28.29.
To break the WR Nick would have to come through 800m in 1:45.5 and hold on for another 200. Is this possible? Looking at his 1500/800 ratio I'd think no - but looking at his 400/800 ratio I'd think...maybe.