One of biggest problem of mature companies is becoming complacent. They used to make money, so they believe this is the time to gain. There is no more need to strive for the success. They are already there. Things do the way they used to be, etc...
Wrong! This is so wrong because those who do not think this way will be soon ahead of you. They will eat you for the breakfast if you do not compete, if you do not try becomming better, doing more and achieving things greatest than those you already have achieved.
So, wake up and find out what you can do today to be one step ahead of your competitors tomorrow! :^)
P.S. You may also research for "destructive management" to get more insights on how to manage a company that have signs of becoming complacent.