Willison enters the final 12 months of his deal on November 1 and will be free to talk to rival clubs then.
Brisbane have signed Warriors veteran Mitch Barnett for 2027 with Haas set to head to South Sydney next year.
And despite significant interest in his services, Willison appears reluctant to follow Haas out the door.
On Tuesday the Broncos front-rower downplayed the lure of signing for the PNG Chiefs and said: "Brisbane's home".
"I want to keep (myself) at the Broncos. I want to stay here for as long as I can," Willison told reporters.
"But at the end of the day, I'll leave that up to my manager and see what's best for me and my family.
"They (the Broncos) have given me everything, to be honest. Since I was 15, they brought me over, had trust in me. I like the boys, it's a great culture here and this is my family."
Willison has started the majority of his games for the Broncos this season with Haas and Patrick Carrigan both sidelined for big chunks of the year.
The 24-year-old New Zealand international has been one of the few bright spots for the Broncos and he claims he is ready to be the long-term leader of Brisbane's forward pack.
"I think this year through the run we had, I definitely stepped up so hopefully I can just keep moving forward to next year," Willison said.
"He (Haas) has definitely helped with my maturity, growing up and doing this sort of role and helping me be comfortable out there to do my job for the team."
Brisbane are away to Canberra on Friday and, if St George Illawarra win their remaining three games, are still a chance of claiming the wooden spoon a year after winning the premiership.
Coach Michael Maguire was ropeable with his side's performance in last week's 40-6 loss to the Warriors.
"We've had bad luck with injuries and stuff and had all different sorts of players in, but the weekend's performance wasn't good enough," Willison said.
"There's definitely the care factor there - the boys care - they don't want to let each other down, anyone at the club and our fans."
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