Speaking after Sanchez scored twice in Arsenal's 3-2 win over Crystal Palace on Thursday night, Wenger said: "I am not fearful but as you said that will be a subject that arises because of his contractual situation".
Arsenal defender Shkodran Mustafi jumps for joy after scoring his side's opening goal from close-range.
Having been hailed as "the future of English football" by Barcelona legend Xavi, Wilshere endured a tough few years but produced a fantastic display against Palace, setting up Alexis Sanchez for what would ultimately prove to be the deciding goal.
Palace upped their tempo at the start of the second half, and five minutes into it they were level, good work from Wilfried Zaha fashioning an opportunity which was emphatically accepted by Andros Townsend.
The Gunners took the lead when Shkodran Mustafi slotted home the rebound after Alexandre Lacazette's effort was saved on 25 minutes.
Defender Calum Chambers was recalled for clash as Arsenal switched to a back three
The hosts' equalising goal began as so many of theirs do.
At that point Palace were in the ascendancy but Sanchez's quick double soon killed off the home side's hopes.
Wenger's team required time to recover from that setback, and it was only after a lethargic clearance from Christian Benteke - also the Palace villain earlier this season - after the hour that they were gifted the chance they had needed.
With a brilliant chipped-pass from inside his own half, Jack Wilshere - often a peripheral figure this season - sent Sanchez into space in the Palace area and, after he impressively controlled, the Chilean routinely poked beyond Speroni.
Palace showed no sign of getting to grips with Arsenal, but they managed to avoid falling further behind before the break - Ozil tried to square to Sanchez when through on goal, only to get it all wrong.