In light of the final cover of ToM, which doesn't show Mat wearing the foxhead medallion, it seems more likely that the medallion will be either left in Caemlyn or even be destroyed before Mat makes his trip to Finnland.

A confrontation between the gholam & his targets (especially Mat and Elayne) seems also very likely, if Mat has to spent several weeks in Caemlyn, so that the gholam can catch up. Elayne is anyway there.

I think it's possible to kill the gholam by using the dull dagger, which Elayne has and which can hide you from Shadowspawn, and the foxhead medallion. With those two items you could sneak up at the gholam, under the protection of a kind of "cloak/cap of invisibility" (a theme that is found in some myths, e.g. in stories about Perseus fighting the Gorgons), and maybe force the the foxhead medallion into the gholam's mouth or at least touch sensitive parts of its body often enough so that the gholam eventually dies. The medallion might be destroyed in the process, though. Either Elayne or Mat could be candidate for such a fight, though Mat as the typical hero seems a better choice, especially since he already successfully fought the gholam, Elayne is pregnant and Mat also got his luck.

Would explain the missing medallion and nicely tie up the gholam plotline with yet another reference to a mythical theme.