I think when it comes to certain characters taking over for others in the MCU it needs to be a clear transition. If Cap at some point dies obviously Falcon is great contender for a replacement like recently in the comics. He has the relationship, spirit, moral and development with Cap for the audience to believe this is a move being done for story and the best man got the role. Likewise if Morales was ever to replace Parker. There needs to be a bond and growth there so it doesn't feel forced to the audience. Replacing any character into another role like Cap or SPidey is a tough transition for audiences regardless of race and needs to be handled through story and development.