I had a serious Grade 4 A/C separation in 1983 at 28 years old. Immediate ligament reconstruction surgery. Pain so bad I couldn't eat and lost 20 lbs.
Since then I have needed 3 other surgeries to decompress the joint: bone spurs, arthritis, rotator cuff impingement, etc. Most recent one June 2016. Recovery is very rough and looooooooooooooong. 13 mos and still hurting bad. And full recovery never happens.
Not being dramatic in saying it has seriously impacted my life. Constant pain for 34 yrs -- more than half my life -- and all the physical limitations it has imposed on what was previously a very active athletic lifestyle.
Then again, there are separations that recover quite well. Depends on severity of injury. Grades 1, 2 and even 3 have good outcomes with rest and PT. Hope he has one of those!
Grades 4, 5, and 6 require surgery as they are complete tears of all ligaments and displacement of the clavicle.