Cannon is a man in demand following a fine loan spell at Preston in the second half of last season and Everton are now expected to let him go after signing Beto from Udinese.
However, while a loan was expected, Middlesbrough are set to change the game by going in with a bid to buy Cannon.
Boro have money to spend and are going to try to agree a fee with Everton.
The change means that Sunderland will also have to try to buy Cannon and they will look to do so if they sell Ross Stewart to Southampton.
Preston had made the best loan offer for Cannon, but they too will now have to look to buy the player.
Everton, watching their financial situation closely, are likely to be boosted by an auction for Cannon.
Toffees boss Sean Dyche has preferred other options to Cannon this season, even amid his side struggling to score goals.
