But should Celtic boss Brendan Rodgers intervene and try bring him back to Glasgow?
Midfield isn't a position of much urgency for Rodgers at the moment but, with Scott Brown turning 33 in June, it's probably time that the Northern Irish manager takes a proactive approach in signing a long-term replacement for his captain.
Hibernian's John McGinn is a name that continuously gets mentioned in the subject of players who should replace Brown, but for now McCarthy is a class above the 23-year-old and signing the Everton ace would represent a major statement of intent by Celtic.
Worth around £10 million according to Transfermarkt, signing McCarthy would show that Rodgers is ready to take the Bhoys to the next level and such a transfer fee would undoubtedly reflect their manager's ambition. It's a big figure but also a realistic one, especially if Moussa Dembele's sale goes through this month.
The Republic of Ireland international - who was born in Glasgow - is impressing for the Toffees at the moment and Celtic would probably have to rely on sentiment to get the deal done.
Speaking to The Irish Independent in 2014, McCarthy, who was released by the Premiership side at the age of 14, stated that it was a "dream" of his to play for the Hoops and Rodgers should at least try and offer him the chance to fulfill that ambition at Parkhead.
The former Hamilton and Wigan midfielder is 27 and you have to imagine that Palace, if they get him, would be the last club to have him during his prime years, but surely winning bags of trophies and competing in the Champions League is more exciting for a peak player than being at a perennial Premier League struggler.
Rodgers has very little to lose by enquiring, and so much to potentially gain.