I think the relationship is doomed…

You don’t actually know him yet. He checks many of your boxes on paper, but everything you feel based on one date is a fantasy projection. There are many gaps in your knowledge about him, and you’re excited so you’re filling them all in positively. As you get to know him, there may be incompatibilities and issues that have nothing to do with him leaving. That’s why you can’t jump ahead so far after one date unless it’s because you already know there’s a dealbreaker. Which it sounds like there is, so trust your instinct. Otherwise, it takes time to get to know someone well enough to decide if you want a future with them (and vice-versa).

I’d personally not see it through in this situation, because you’re not in the same life stage right now and won’t be looking for the same things (the best you can do here is a long long-distance relationship). I’m not sure how old you are, but if you’re aiming to settle down sooner than 3-5 years from now if you meet the right person, you should find someone you like who you can spend time with to get to know well in person and who has the same goals as you. If you are young and want to have fun and can handle the separation if you continue to hit it off (and you probably will keep having a good time since having a departure date in 3 months away will keep things light and fun since you don’t need to resolve serious relationship issues together if you aren’t actually building something together), then go for it. But I learned in going for situations like this when I was younger that I was leading myself on, fantasizing, and wasting my own time dating with an expiration date (in hopes love would just find a way!!) and then always needing to recover emotionally for some time after. Life experience can be great to have and you can choose that approach, but if you already know what you want and this situation isn’t it, I’d recommend you keep looking for a better overall match.

You can always tell him to hold on to your number and ping you if he does settle down somewhere more permanently. You can’t wait for that, but hey, if it happens and you hear from him and you’re both still single, then you never know where it might lead.

Just begin seeing him as a friend so you can have practice in dating. No sex though. See where it leads.