I think him and his manager, and probably the broncos, would be looking for a 2yr extension and upgrade on next year... so a 3yr deal.
That gets him through to 22-23yr old and they can re-evaluate from there.
His manager won't want him locked into a long term deal unless he can get huge dollars, but realistically no one is going to throw him $5m for 5yr... maybe someone will throw him 5yr for $3m... but if that's a desperate Sydney team then that requires him to move away and into a completely different environment.
Broncos would love to lock him down for a long deal, but I don't think they want to lock him down for like $500k-$600k.
A possible scenario could see him get $350k-$400k over the next 3yrs... if he's matured at 22yrs old he might consider heading to Sydney, but he could also be our star fullback and looking at $900k+.
If he does explode I'm sure broncos would be happy to look at upgrading and extending whatever deal gets sorted out anyway... like they did with Haas.