We call a natural hybrid which has homogenized, formed its own population, and breeds true a SPECIES. That's how a lot of them came to be! That which is a species now may be three in 1000 years, and that which is a natural hybrid now will be a species in 1000 years. Or 10000. The real problem is humans look at a dynamic, changing picture and think it's a still life, calling the point the line. I often wonder how many current 'species' began as natural hybrids, while in the intervening time their parents' ranges have modified so that we would think it impossible for them to have crossed, or one or both of the parent species maybe even have disappeared completely.