Facts: Current birth rate among indigenous Europeans in most if not all European countries is and has been below replacement level for a few decades. Most population growth in Europe in the last few decades has been from immigration from outside Europe. The birth rate among non-indigenous Europeans in European countries is higher than indigenous birth rate.
Projections (not fact): This trend doesn't appear to be changing and it looks like it will continue for many more decades. If the trend continues, in a few decades the genetic makeup of most Europeans will be more similar to that of non-European ethnic groups than to that of people who have lived in Europe for tens of thousands of years.
Arguments (assuming projections are true):
a) the projections above are a bad thing if you are an ethnic European and you predominantly carry genes that split from the ethnic groups of immigrants tens of thousands of years ago.
b) the projections above don't matter
c) the projections above are a good thing
State why the projections are likely to be wrong, debunk argument a) or justify why arguments b/c are correct. Proceed.