It's definitely a sad day as he paved the way for Nintendo and others to shape gaming into what it is today.
However, with his passing, what will happen to his shares in the company? Will it remain within the family or be sold off to numerate parties... Yamauchi had a large stake in Nintendo and will have still had sayings on the companies direction etc. with them having struggled as of late and his typical Nintendo does as Nintendo wants mindset, could things now change for the company?
Could they perhaps start to evolve a little more, maybe even start to embrace western ideas with their future consoles and gaming (online, accounts etc)?
Time will tell, but indeed it's sad that he's passed first and foremost.