It was his ego refusing to recognise or acknowledge his decline was the problem.
That same ego refuses to be an impact sub, as that would be belittling to him.
As for building a team around him, yes that would work for a much smaller lower level team. But any team above a certain level is never going to change their plans or style, and sacrifice the roles and impact of other players just to accomodate him up front (not at the level hes performing at these days.). Ole done it and it contributed to him losing his job. Rangnick tried to change it and got no response from the players, EtH was having none of that. "Your a squad player now." The fact Ronaldo seen that disrespect rather than assessing his own levels, shows he'll prob settle for nothing less than being the main man until he calls it a day.
If he does decide to leave Saudi, will be interesting who would take him (willing to make him the main man), and who he would want expect to go to