It's all about his health. If he can sustain good health for a year or more, allowing him to practice hard and play a good amount of rounds, there's simply no reason why he wouldn't be able to get back into the top 5 in golf. At his age (42), I don't ever think he'll ever dominate golf again, but he can certainly win multiple tournaments again and can even win a few more majors - he was still #1 in golf less than 4 years ago.
But I have no idea if he can maintain that level of physical health. Not sure if anyone does, which is why I would never take a bet for or against him right now. For now, it's just about the process of getting back into playing shape and tournament shape. If he can be moderately competitive the next few months and even get back into contention at a few tournaments, you know he'll then have a shot at Augusta, where he came close in 2015 despite not playing much and hurting his wrist in the last round.