This will effect FR alot more than U2.
U2 are catering for the business passengers and holiday makers who are heading to the main resorts (PMI, ALC, AGP, FAO) etc. where as FR have alot of flights to places such as Seville and Granada where the demand is not so high - and they have to fill more seats!
U2 is getting a big base at LGW which has more of an appeal to business passengers compared to FR's biggest base north of the city.
Expecting FR to be hit more with the current problems than U2, who seem to be doing quite well during this so called 'crisis.'