I foresee two possibilities.
2 seconds sound clip from the Back to the Future Part II movie soundboard.
You can hear this line at 00:25:58.493 in the Blu-ray version of the movie.
Quote context
[...]
- We'll arrive shortly thereafter, get her out of there and go back to 1985.
- You mean I'm gonna see where I live? I'm gonna see myself as an old man?
- No, no, no, Marty. That could result in...
- Oh, Great Scott! Jennifer could conceivably encounter her future self!
- The consequences of that could be disastrous!
- I foresee two possibilities.
- Granted, that's a worst-case scenario.
- The destruction might, in fact, be very localized, limited to merely our own galaxy.
- Let's go. I sure hope we find Jennifer before she finds herself.
[...]