There have been long term studies on length of sobriety and how that effects future sobriety. The one I wanted to cite is behind a paywall but here is the general takeaway from the study.
*Only about a third of people who are abstinent less than a year will remain abstinent.
*For those who achieve a year of sobriety, less than half will relapse.
*If you can make it to 5 years of sobriety, your chance of relapse is less than 15 percent.
Having said that...I got sober in 1990 and relapsed in 1996 after over 6 years. I got sober again in 1997 and relapsed in 2004 after over 7 years. I got sober in 2013 and I'm still sober, and I'll celebrate 8 years in about 4 months. So making it 5 years didn't keep me from relapsing, yet I seemed to "breeze" by the 1 year mark each time. For me it was a matter of becoming complacent (what AA refers to as "resting on your laurels"). After several years I stopped doing the things that I had been doing to stay sober. I didn't consciously stop doing them, but I guess you could say I slowly fell out of the habit of doing those things and took my sobriety for granted. Each time I relapsed all it took was a good "life crisis" and my defenses were weak.
The first time I relapsed after 6 years it lasted for just under a year and the damage done was fairly minimal. The second time I relapsed after 7 years it lasted for 8 LONG years and it nearly killed me. I believe that people can recover from alcoholism but can never be cured. There's another old saying in AA that goes something like "you can recover from a gunshot wound but it doesn't make you bulletproof". I now treat my alcoholism like someone would with a chronic illness where if you take your medicine every day you can keep the illness in remission. My personal medicine are the 12 steps that originated in AA and have worked for millions of people. I have found that if I live by the principles of the 12 steps on a daily basis I stay on solid footing, and there hasn't been a "life crisis" I haven't been able to weather going on 8 years now.
And if AA and/or the 12 steps aren't for you, find something that is. Some type of plan that helps you stay sober and can withstand whatever life throws at you...good or bad.