I can't claim to be an expert but would've thought she's already been around longer than Katie Perry?
Katie Perry has been a huge global star for 7 years, Taylor Swift, about one year. I'm not saying she will dissapear from the music scene, I'm saying I doubt she has what it takes to be a huge star for long periods of time. In example, Lady Gaga still sings today but if you compare her popularity/sales to, say 2011, you can only conclude she's not huge anymore.