Honestly I'd be okay with Twilight becoming an Alicorn either by the end of the series or if she were to possibly "transform" whenever she wanted. When I first heard about the rumors, I cringed. hard. The idea itself just made me want to dismiss it as false immediately. (which it is, right?) The entire thing sounded like it was ripped out of a MLP fan fiction or something. But, after watching the first episode of S3, It intrigued me further. I opened up to the possible fate for Twilight Sparkle. With the possible hints with Luna holding a book near the end of Episode 1's credits, and Twilight "moving on to next level of her studies", I was more and more leaning toward the rumor of it being true. So, if it ever does happen, then I won't complain. Like many of you have already explained, Studio B knows how to pull things off really, really well. If they ever do try to attempt this, then I know it's in good hands and we don't have to worry.