Morientes has been impressed by the impact of Gonzalo at the Club World Cup.
He told Radio Marca: "I loved Gonzalo; it's great news for Real Madrid. I've always said that youth players have to give their all to get playing time and be relevant in the first team, and Gonzalo has done just that.
"If Real Madrid was thinking about (Ante) Budimir (Osasuna), (Dusan) Vlahovic (Juventus) or things like that, they would have to go to the market and spend a good amount of money... I think Gonzalo's deal is a perfect fit.
"Gonzalo will have his minutes and his impact, but in this Club World Cup, he's undoubtedly the big news."
Morientes added, "I would like Endrick to go on loan, so he can get the minutes he hasn't had this year, and for Gonzalo to take over Endrick's role."