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If you ask me I can say Ronaldo is not even having as good a performance as he had before and he can never be the same good Ronaldo we saw from him back in Real Madrid because of his getting old and that's why Portugal should think about finding a replacement to fill the place of Ronalod in this team because so far Portugal didn't have any interest in not using Ronalso for some games and use the younger player to give them more chance. Now Ronaldo is more like a marketing brand for Saudi Arabia and than a player for Portugal.
Here I fundamentally disagree: the reason is so obvious that I am surprised you yourself can't see it. Isn't it very easy to set the conditions under which Ronaldo should not be replaced? It is in my opinion and here is the evidence.

Ronaldo is by far the best goal scorer except for Fernandes who is only one goal behind him. For what reason should Portugal replace him now? I agree that they should have someone being prepared in the background who can take his position as soon as the time has come, but if he finishes a year as the top scorer of the national team, it would be stupid to leave him out of the team.
The reason for Ronaldo to be at the top of the table is clear to me. Just imagine a player with good finishing skills in a team while there is no other player like him and they all believe he is still the best in the World and they didn't give any chance to the other players to take his place.
I know Ronaldo is a good player, but still, players like Fernandes can have more chances and with the more chances they get, maybe we won't see Ronaldo in the top side anymore.