I believe United's management still wants to keep Ronaldo. His performance may have decreased, but Ronaldo gave extraordinary encouragement to other players not to give up easily.
but all will also return to Ronaldo's decision. but I don't think Ronaldo will leave United in his current state
I suppose there's also the question, given that his performance over 90 minutes is definitely not what it used to be... which teams would want him and could afford to pay his huge wages?
Teams at the very top, who are fighting for the Champions League, would likely not want him as although he's still very good, he's probably not good enough given the financial outlay.
Conversely, he could get huge wages by going to a lesser team somewhere rich, USA maybe or the East... but that would probably not satisfy his desire for top-level football.
Man U may be the best it gets... good but not at the very top, able to pay the wages, and where he's worshipped as a hero.