De Koning's current deal with Carlton is set to expire at the cessation of this season, with the 23-year-old currently weighing up his future in the navy blue.
The 203cm ruck-forward, who has played 32 games at AFL level since joining Carlton as a second-round selection in the 2017 National Draft, could be valued close to $800,000 or more per season for his next deal should he manage to meet the ceiling those believe he can in 2023.
Should De Koning manage to take the ruck reins and provide plenty of power in attack, the Mt Martha product is likely to have numerous rivals circling.
The Blues' plans to lock away De Koning may hang on the opportunities the key position talent is handed this year, as well as the club's salary cap situation - having handed long-term deals to Charlie Curnow and Harry McKay last year, while key figures Patrick Cripps, Jacob Weitering and Sam Walsh are also signed for the coming seasons.
While interest in De Koning is said to be coming from St Kilda and Essendon, Carlton could be blown out of the water by Sydney, with The Age reporting the Swans are weighing up an eight-year deal for the versatile tall.
That offer would come 12 months after veteran forward Lance Franklin's lucrative nine-year contract reached its end, with the four-time Coleman Medal winner signing a one-year extension for 2023 for what is expected to be his last season in the AFL.
Should Franklin retire, De Koning would be seen as the man to potentially fill the key-forward void for the Swans, who will be hoping the big-bodied utility can partner young star Logan McDonald in attack.
De Koning would also aid the Swans' ruck dilemma, with 32-year-old Tom Hickey still seen as the club's leading man in the middle.