Currently playing a 13th level character who started at level 3 about 18 months ago (with a few months off at one point to give the DM a break, during which I DMed an 8 session or so mini-campaign). I expect that campaign to continue for awhile yet. Maybe not all the way to 20th, but probably a few more levels anyway.
For what it's worth, we're three couples plus one guy whose wife doesn't play, and every single one of us has kids, ranging in age from 4 months to 7 years. (Two new babies born during this campaign) One couple who both play had a baby in May and have mostly been Skyping in since then. We're off for a few weeks now for the holidays but generally play 2 or 3 3-hour sessions a month, leveling (by milestone or just fiat) about every 4 sessions.
We collectively spend a lot on babysitting, but rotate hosting to spread it out. If it's a high enough priority it's definitely possible not to have life get too much in the way.