In an interview with guardian.co.uk Shigeru Miyamoto talks about his personal plans for the future.

When asked if he ever considered writing a book about game design or teaching, the Nintendo superstar answered:

"When I leave the company, I would like to work with young people and teach them about developing. Though it wouldn't be like [traditional] teaching, more explaining how we think and how we interact with the user. For the development process, practical learning is important."

Following this, Mario's creator also says "It would be a joy for me if someone who was working with me became a big success", so he certainly seems to be interested in bringing up new talents.

Fear not though, Miyamoto said he's not thinking of retiring yet, so we can continue looking forward to his new games!