I (19/M) have a super weird relationship with my ex/current FWB or whatever (18/F)

We dated for two years in highschool. I entered college one year earlier than she did (so she's still not in college). I didn't want to miss out on the college experience, so I told her that I wanted to break up with her when I went to college, although I still liked her a lot and that if possible, I'd like to see her and only her whenever we were in the same country (since I go to college overseas, and she will to, but to a different country. During breaks/holidays we will both return to the same country). She said that she was okay with this.

Okay, great. So I still text her everyday and Skype her maybe like twice a month. Meanwhile, I'm still getting with other people in college. I don't tell her about people I'm getting with because she doesn't ask, but when I saw her in the holiday in December she asks in a very roundabout fashion 'so have you gotten off with anyone?' and I tell her yes. She seems a little shaken, but otherwise okay with this.

To the best of my knowledge, she hasn't hooked up with anyone. We both acknowledged (although not explicitly) that we would not hook up with anyone we both knew because that would be a dick move. I've told her numerous times that I don't want her to tell me about people she hooks up with because I don't want to know.

Caveat: I'm pretty sure that I'm the first person she has ever dated. She constantly talks about how she's not gonna hook up with guys on nights out during uni because 'that's slutty' but I've seen too many supposedly "good girls" get with multiple guys in college so I'm not putting too much weight in those words. I've hooked up with "good girls" who turns out to have had a boyfriend (I didn't know until after the fact).

I guess I don't have too much of a problem, except for the overwhelming fear that she'll eventually hook up with someone because a) she's good looking and b) she'll be going into college soon and c) our 'conditions' mean that she's totally allowed to do whatever the hell she wants at uni (as am I). At that point, though, I'm really not sure how I would react. It's entirely unfair, and I know that I 'should' be okay with it, but I really don't know if I would still want to talk to her if I ever find out (from mutual friends or whatever) that she hooks up with someone else. That is, I don't know if my continued feelings for her will remain.

I'd still very much like to end up with her in the long run (as cheesy as that sounds) but we both acknowledged that long distance would probably not work, and that neither of us would want to be tied down during college, which is why we didn't pursue a long distance relationship.

I guess the question is: how do you guys see this progressing? Is there a chance for us ending up together after college?

As it stands, it feels like we're in an open relationship with each other. We will go out for movies and stuff as well as hook up whenever we see each other, but we'll (jokingly?) say that we're being 'just friends'.

tl;dr Still FWBish with ex, broke up for logistical/college experience reasons, we are in different countries but hook up whenever we're in the same country, does anyone see the relationship continuing after we graduate and end up in the same country?