I continued to hang-out and do stuff with my 'core' friends for about 2 years I guess, which also brought us into contact with a dozen other non-core friends on occasion, every couple months or so. This began to dwindle through the 3rd and 4th year post-graduation, as we all started to do our own things, a couple friends got married, et al, I moved 120 miles away after finishing a local community college.
For the last five years, approximately, I haven't seen nor talked to a single friend from high school except in passing a couple times. It turns out that I hung-around with a bunch of real dorks and we really had little in common after I went from a high schoolish maturity level to an adult. Some of them are still trying to party every weekend, smoking pot, acting...well...like high schoolers.