The 31-year-old striker, who sits joint second on the A-League scoring charts on 10 goals, has been a leading catalyst in piloting Phoenix within reach of the A-League playoffs.
The club sits eighth, just three points adrift of a finals spot, as it heads into its final five games of the regular season against Melbourne Heart, Newcastle Jets, Adelaide United, Sydney FC and Melbourne Victory.
And it was anticipated that tying up hit-man Huysegems, for at least another season, would be a top priority.
But his agent, Melbourne-based Dragan Jetvic, revealed that Huysegems will now look elsewhere in the A-League, Asia and possibly back in his native Belgium after being unable to reach terms with Phoenix, which is locked into a rigid pay structure which offers little room to manoeuvre.
"It would be a shame to see Stein go because his performances and goalsoring prowess have helped lift the level of the competition this season," he said.
"He has 16 caps for his country and offers a degree of pedigree which has been there for all to see.
"But, in terms of negotiations, it's not looking too promising at the moment."
Huysegems, who turns 32 in June, has been offered a one-year extension but the renumeration on offer does not "meet his expectations" with the former Feyenoord, FC Twente, Genk and Lierse forward now all but resigned to leaving the club he joined in 2012.
Huysegems, who is looking for the security of a two-year contract, believes he can retain his potency at A-League level for at least two more seasons and will now use the final five rounds - and possibly the finals series - as an audition to catch the eye of other clubs as he looks to a new career destination.