I stopped playing for a few years. I stopped playing at about a 4. I've been playing again for few years and have never got back to where I was. That's mainly because I don't practice like I used to and my irons aren't as crisp. I hit the ball as far but no where near with the same ball striking and I'm not consistent off the tee nor do I have the same touch and feel around the greens. Honestly, I was very frustrated when I started playing again because I expected to shoot similar scores to when I stopped playing. I adjusted my expectations and realized that I don't play as often and I don't work on my game like I used to and the frustration was gone. I started really having fun again realizing that I'm lucky enough to be a decent golfer but I'm not at the point where I'm shooting my career rounds...
I guess it depends on your approach. If your determined you can get it back. I still plan to keep improving but by no means do I put in the effort I would need to get back to where I was at my best. I get risky and try shots that I have no business trying but I still have fun and I'm happy if I keep it in the low 80's and I'm happier if I keep it in the 70's. That said, I want to birdie everything! Or make that awesome Par save... or well, just find my golf ball...
Good Luck, Welcome Back, and Have Fun! Sorry I was no help! My only real advice, don't expect to have that same consistency you did before you quit the moment you pick everything back up.