I agree with minty melody, there shouldn't be anymore alicorns than there already is. Twilight has a important purpose. If all of mane six were alicorns the magic of friendship would be at risk. If the mane six were alicorns they would have so many duties that they would have very little time together making there relationship almost not a relationship at all. Plus if they were all alicorns that would make twilight and her element (the element of friendship) usless as well as spreading the magic of friendship. Making all of them as useless as twilight. One last thing, there would be too much magic which would throw off the balance of nature transcending the barriers of which would create a massacre of chaos which would put the world at risk of losing their faith, hope and strength as well as peace in the land. (I have a point you know!)