Barkley has just seven months remaining on his contract at Goodison Park, and there has been strong suggestions that the England international could move in January.
Barkley has not shown a willingness to pen new terms at Everton, and the Toffees won’t want to lose the midfielder on a free transfer.
Tottenham Hotspur and Chelsea have both been touted as potential destinations for Barkley.
But Townsend fears that if Barkley ends up at Spurs or Chelsea he could spent a lot of time on the substitutes’ bench.
"He has had a seriously nasty hamstring injury which hopefully is not going to give him any aggro in the future. But he's a difficult one to put a price on. Nobody doubts his ability it is about where you play him. Which club would he want to go and play for?
"He wants to be a significant player but Danny Drinkwater left Leicester to join Chelsea. He's a wealthier man now and good luck to him, but in terms of his football wealth, in terms of playing, is he getting satisfaction from it? In a year's time the answer might be no.
"You have to have ambition but you have to be realistic too. Clubs will sign players like Ross Barkley and sit them there and not necessarily use them as much as you're lead to believe they will. You have to use your loaf a bit and make sure you can go and play."
Barkley has not featured at all for Everton this season due to injury, but he is expected to return to fitness soon.
Whether Sam Allardyce will use Barkley remains to be seen, as he has already stated that he only wants players who are committed to the cause at Goodison Park.
Allardyce is still unbeaten as Everton boss, avoiding defeat during his first seven matches in charge.