A large portion of the reason the NES was so successful and why the industry is so successful today is that Nintendo created a business model which was more stable and secure and protected the interests of all stakeholders in the industry. By the end of the generation retailers felt far more confident in stocking games from "well known" publishers, consumers felt far more comfortable buying games, and publishers were in a much better position to create reliable revenue from the industry.
Some people would say that we would just be playing PC games without the NES but I'm not sure of that. The PC industry faced the most rapid growth in the wake of the NES in a large part because publishers had recovered from the industry crash and were re-investing their profits into markets where there was opportunity ...
Beyond that, Nintendo in general (and Myiamoto in particular) is very responsible for creating many orignial elements which were evolved into the foundation that many genres are based on today. While most genres might have evolved in a similar fashion without being influenced by Nintendo's work, I can't help but think most games would have ended up being very different.
