Europe suffers from the dilemma of education whereby more educated persons are less likely to decide to have children. This is paradoxical since well-educated parents are typically the most ideal parents a child could have, and the resulting children are the best economic outcome any economy could ask for. Accordingly Europe should be working on incentives for improving birth rates.
I personally think that birth rate affects demographics by default. In Europe having less birth rate is not that bad because right now the world is getting crazy populated, but maybe in the future that means it will be harder to get the birth rate back up and we will start to get less populated.
The demographics of Europe can be improved with higher birth rates. This is because the people native to the countries in Europe deserve to keep the country for themselves. Their money and benefits should not be going to so many outsiders. Ethnically, the Europeans would be helped by increasing their birth rate.
The dwindling birth rates in Europe do indeed pose a demographic problem for the future, but the only real solution is to encourage more fertility among Europeans. Mass-immigration is not a solution, since it doesn't make up for a nation's lost population, it just completely replaces it with a new population. For example if Germany's birth rates are low, and the lost population is replaced by foreign Turks, then the German nation has not been helped, it has just been replaced by a new foreign population.