I had an issue with this while finishing up classes at school, although I understand being a college student isn't really the main demographic for this article. I had a group of friends that I met with only through convenience (we were all in the same fraternity, and then I quit).
After some time, one of the guys made a multi-way text/chat group on WhatsApp and it gave us all an opportunity to bullshit amongst each other about whatever we felt like. The best part was that it didn't leave anyone out of the loop, and held us each accountable for responding to attempts to get together. Most of the time the interactions are pretty pointless (cracking jokes at someone, sending links to a funny picture or article, changing the group photo to a hotter girl than the last one someone put up, etc), but it's just a good outlet to stay in sync with one another, even if we don't all have time to hang out. I'd recommend it to anyone who connected with the article.
Set up a Teamspeak or similar voice server. Like the guy above I'm only in my lower 20's at this point but it's the single best move I've made in maintaining friendships with people I'm no longer physically close to. My friends know that they can hop in any time they want and we can have a great time chatting or playing a game together.
I think the more accessible you make it to keep in touch the better off your relationships will be, but there's no getting around the simple fact that friendships require effort from both parties to maintain.
After some time, one of the guys made a multi-way text/chat group on WhatsApp and it gave us all an opportunity to bullshit amongst each other about whatever we felt like. The best part was that it didn't leave anyone out of the loop, and held us each accountable for responding to attempts to get together. Most of the time the interactions are pretty pointless (cracking jokes at someone, sending links to a funny picture or article, changing the group photo to a hotter girl than the last one someone put up, etc), but it's just a good outlet to stay in sync with one another, even if we don't all have time to hang out. I'd recommend it to anyone who connected with the article.