A simple definition like that makes it very obvious what the problem is: a potentially perpetual refugee status. With that definition, a refugee who refuses asylum in a perfectly safe country with good living standards could still be a refugee, because they at some point were forced to seek refuge.

A more robust definition of 'refugee' would provide good ideas for when a refugee is no more a refugee.
Not checking for EU countries or the UN, but for the US:

U.S. law allows certain people who cannot or do not want to return to their home country because of past persecution or the danger of future persecution to live in the United States as refugees or asylees. However, the source or danger of persecution sometimes disappears after a refugee or asylee has already been granted status but before he or she has obtained U.S. citizenship. The question then becomes whether the person will be allowed to continue living in the U.S. under these changed circumstances.
For example, if you obtained asylum on grounds of political opinion because your home country’s government persecuted you as a member of the opposition, and your party has now come to power, then you might wonder whether the U.S. government could terminate your asylum on account of this change in your country’s conditions.
The answer will depend in key part on whether you are a refugee, on the one hand, or an asylee, on the other.
The main distinction between these two is that ordinary refugees apply for their status from outside the United States and resettle in the United States through the U.S. Refugee Admissions Program (USRAP), while asylees are a special type of refugee who apply for their status directly from within the U.S. (or from a U.S. border). Because of this difference, asylees and ordinary refugees get treated differently under U.S. immigration law.
If you are a refugee, then you are unlikely to lose your status in the United States on the basis of improved conditions in your country, such as a new government, a newly signed peace treaty with a rebel group, or a new law protecting people who were being persecuted for the same reasons you were. However, loss of status is more of a possible concern if you are an asylee.
http://www.nolo.com/legal-encycloped...e-country.html

But that's for the United States, and it is relatively difficult for Syrians to apply for asylum given the geographic barriers.

What indicates that no type of refugee in Europe can ever lose that status? At any rate, in most cases it shouldn't really be relevant anyway once the process of naturalization goes through. Remember that the plan has so far been for either settlement or deportation, not for locked-down camps as in the neighbors of Syria.

As for more general questions for the future and around the world, well - why is it an issue there either?