1st of all the N64 would not suddenly sell much more if PS1 didn't exist. (There are reasons but I will not go into it.)
2nd All the PC developers who jumped on Playstation would not jump on consoles
3rd Xbox won't exist
4th Nintendo would still have its strict 3rd party restrictions so no massive number of games increase
5th Gamecube would still suck (But we will still have Rare me thinks)
6th Sega would still be in the market :D (I find that a positive thing)
Edit: Gaming would be smaller but recardless of Sony joining or not gaming will not be mainstream not than not ever








