Barcelona currently depends on Messi more than Messi does on Barcelona.
You don't need to say this. It likely you underestimate Barcelona without Messi. Are you a Messi fan or a Barca fan?
There will be another player to be the successor of number 10 if Messi leaves Barcelona. And I am sure he will be as good as Messi in the future if Barcelona has more chances.
Despite his high salary, Messi is also generating a lot of income for the club.
I can agree with this. Sure, it is the fact. Messi is the iconic player in Barcelona. As he is one of the best players in the world and even in the history of football, his presence in the club will be profitable, especially if we consider partnerships and Merchandise.