Football is going to be a very hollow place when he retires. I didn't feel that way with Ronaldinho or any player in the last 20 years.
It's also intriguing, yet scary, how the Club will be when he does go. The last 10 years have been the most successul period in the Club's history. Messi is mostly responsible for that.
I don't think Real Madrid will be in a position to take advantage of it though. Their Galactico period is dead and burried, and they've been underwhelming with Cristiano Ronaldo in their side for the last 8 years, 1 title is pretty bad with him and all the money spent.