A lot of Slater's game is based on his speed.
The older he gets, the slower he's going to get. There is a point at which the additional wiles an older player gains from experience aren't enough to off-set the loss in speed.
Slater could probably play for another 2-3 years if he really has a burning desire to and a club could be found. Problem is that now his age is counting against him, so anyone who does hire him knows that those 2-3 years will be all they'll get from an increasingly slow and injury-prone player. Could be worth it if you have a gun fullback or winger who's 2-3 years away from being ready for the full NRL or Super League grind, otherwise he's just a stopgap measure while you try to find a long-term solution... and given the money you'd need to shell out to afford him, you might not be able to find and retain a top-flight replacement for Slater either.
Ultimately it'll come down to how much he wants to play NRL, and/or how much the Super League might throw at him. He's already got his foot in the door with media roles and I'm given to understand he could make a decent fist of things as a trainer/owner in horse racing too, which he also enjoys. Now might be as good a time as any to transition to a post-NRL career.
