If I remember correctly, I'm pretty sure that in the very beginning of the PC gaming lifespan, PC gaming was actually very much the same as console gaming. During the game-crash of 1983, the PC games on the market where mostly ports of console games and arcade games. Often these ports were actually better on PC. Console manufacturers were scared because the PC could basically do exactly the same as consoles, with the SAME games, and MORE. The PCs such as the Commodore 64 were greatly outselling the consoles on the market.Ever since computer gaming became little more than a few guys making hacks on a mainframe, and something similar to PC's became available, it would appear as if home computers were a direct competitor to gaming consoles, but it seems to me that games played on each system were strikingly different.
Eventually PCs and consoles started sharing games, but I believe that was rare. While Nintendo players struggled with Castlevania (which was released for MS DOS three years later, in 1990) PC gamers were engaged in other genres, like adventure or strategy. But consider the cost of a home computer back then (thousands of dollars vs. $300 MSRP for the NES), and I don't see how it could really put home consoles out of business. Maybe later when the cost of home computers lowered down, but by then I believe most remaining consoles were pretty well established with their own in house franchises.
In general, yeah, I think so too. Nintendo shaped and defined many genres and common modern practices. But PC gaming, at least as far as original PC game genres, would have persisted regardless. I don't see how Nintendo influenced, for instance, Maniac Mansion, Betrayal at Krondor, Baldur's Gate, Master of Orion or Civilization.
What Nintendo did, more than anything else, is put pressure on the competition. The reason why the video-game market in the USA was about to crash in 1983 is due to the lack of quality games and the market was over-saturated with crap. Developers overestimated consumer demand and thought they could get away with poorly coded arcade ports and other crap. Nintendo brought the video-game industry in the USA back to life for both the consumers and the developers by delivering a bunch of extremely high-quality games that were far superior in quality than anything on the North-American market at that time.


