Not quite sure what your saying in your reply, maybe the reply has errors. "Well the hasbro did it", are you trying to say that Hasbro has done so? If so I would disagree, as no where as of yet does it say anywhere that Twilight will be immortal... or even Celestia and Luna technically, but I will put such aside. I look at it like this, Twilight Sparkle will become an alicorn much like Princess Cadance and from what I have seen there is reason to believe that Cadance ages like a normal pony. In the flashback it shows Princess Cadance as a teenager, and later when one sees her is is an adult. Most likely she is actually near Shining Armour's age from what has been shown and I feel the Canterlot Wedding shows that she will have a normal lifespan. Twilight I feel, if she stays an alicorn, will be the same and as such will not outlive her friends... unless it is shown that Princess Celestia and Princess Luna will be stepping down. Even then I feel the writers will work it so that Twilight and friends will be able to stay together.
I know. without her friends, The Element of Harmony will be powerless to defeat the Villain, the ponyville will be a disaster. All the ponies will be extinct like if our world won't have friendship. there will be no Inspiration.