Of course they can. They already have by virtue of there being a Paris show, and technically a 6th O2 show. Financially its worth their while to do a european tour of some sorts, and its also in their intrests as seb has said to hold off on announcing more dates until this inital burst of o2 shows sell out. Imagine how many fans from all over europe will travel to the o2, which is necessary if they are to sell out 6 nights. Now imagine how many of those people would not travel in the current economic climate if they knew there was going to be a show in their own country.