He's starting that process over again. It's 4-6 weeks, not months. He'll be cleared to practice in likely a week from what Gar has said. Hell the surgery took less than 15 minutes and he walked out of the office putting full weight on the leg. This is a minor set back. The mental part will be the hardest thing but from everything his teammates and coaches have said, he's in high spirits and is ready to bust his ass to be back in time for the playoffs.
Lots of players don't have their MCL or part of them and are having or had great careers. Westbrook, Wade, Blake Griffin, Ron Artest, and others. Heck Wade has played his entire career without an MCL in his right knee. You can still have a great career after this surgery. I'm just praying this is the last of the knee surgeries because seriously, what kind of a fucked up God would punish a guy like Rose over and over again but give a monumental douchebag like Lebron a free pass all the time?