No, 5,000m is not very tough for El Guerrouj.
In the 1500 he had to run a 1:46 800 t just barely get rid of Lagat.
This year Baala, Ramzi, and Kipchirchir are all there, fast, and ready to kick him down. The WCh race will not 3:30, but probably 3:32-3:35, ideal for kickers.
On the other hand, there is no one at 5,000m who can kick with El Guerrouj. Bekele exhausts himself trying to get away from El Guerrouj in the early going, and even though he can run 26 for the last 200 regardless, El Guerrouj is always faster. With his new tactic of simply waiting until the last 200 and mowing down whoever is in front, no one can beat El Guerrouj at 5,000 unless they maintain world record pace for 11 laps and he is not in shape or put in some ridiculous move from 2K lap like Komen did against Gebrselassie. Even then you'd need a 57 right in the middle and have to not die off yourself to win.