Newcastle United are at risk of losing one of their key players this summer. While there is a hope that Bruno Guimaraes will stay at the club for at least one more season, Newcastle do not have the midfielder’s future in their own hands. Indeed, Guimaraes has a release clause worth around £100m in his contract, which is believed to be active until the end of June. As happy as he says he is at St James’ Park, the fact is that the club would be powerless to stop him leaving should an interested party stump up that kind of cash. Manchester City have most recently been linked with a move for the 2…