Inter would be a good option is Ronaldo will stay in Juventus..
Then, we are going to see those two big players playing in the same league again and the competition is going to be strong again.
The new El Classico is going to be Juve-Inter.

I'm not sure if Messi will go to Inter, if it's a real surprise. Can Inter pay for the messi release clause? Interestingly there is no official news yet, we will wait.
Regarding Ronaldo, there are many rumors that he will leave Juventus. The club is no longer able to pay Ronaldo's salary, Ronaldo himself reportedly wants to leave. The club's next goal is PSG. If that happens there won't be a classic match like their time in Spain.
So yeah.. Some rumors swirling around that Barca's president is ok with unloading Messi and his huge salary asap.
I think there are three clubs who could have the money to take him in right now... Inter, City and maybe PSG.