I feel that there are now a number of changes happening globally which have not been seen on such a scale in previous centuries. There seems to be a bigger flow of people from country to country; there is greater conflict between belief systems and there is the globalisation in commerce and industry encouraged by the Internet. The nation state is under attack from these forces as well as, in Europe, from the political drive to a European Federation.
If a nation state is to withstand these pressures, it must promote its culture and identity very fiercely. However there is an argument for thinking not of nations but of territories which anybody can move to and make use of. You take your cultural identity with you, but then you must accept that neighbours may have very different attitudes and patterns of behaviour and that you should make no attempt to alter them. If you do not, then there will be conflict and social tension. For example many UK citizens are taking their culture with them to a permanent home in France or Spain. Asians and Africans are moving to Europe and establishing their own ways of life with little regard to local sensitivities.
There are indications that this is happening whether we like it or not. The Home Office has lost control of UK immigration, but so have other countries such as Italy and Spain. The UK has tacitly agreed to a big influx of people from the new EU countries. We no longer insist that the UK is a Christian country, but have accepted a multi-faith, multi-cultural society. This does not show any real determination to maintain this nation state.