manchester united could still sign radamel falcao permanently .
chief executive ed woodward held talks with monaco on sunday .
woodward told monaco the club would make decision at end of the season .
under the terms of the loan , united would have to pay £ 43.5 m for striker .
monaco are willing to negotiate fee however after falcao 's poor loan spell .
falcao has managed just four league goals for united this term .
monaco manager leonardo jardim believes falcao can rediscover his form .