I LOVE xc but put me in the NO category. A relay is simply not nearly as compelling as watching the best individual athletes go mano-a-mano. The team medal at world xc is not nearly as compelling as the individual medal. Plus 2.5 km is a joke distance.
If world xc is to return, it should a) go to the winter Olympics or b) replace the 5k of 10k in the summer Olympics. You could even have team scoring for a team medal.
But I personally think adding all of these sports/events is stupid. Stay with the classics. Personally xc was a classic and never should have left. But if you want to make running more popular, make it easier for people to double. Don't dilute competitions and make them less compelling by adding a ton of relays.