Any reason why do you think Sega would have become bright with N64-CD being a thing (so they would still have a CD company there to preassure them) or Sony not being in the Market?
They had early release of Genesis against SNES as well. So all point that Sega would have done basically the same mistakes.
About your expectations of Nintendo basically doubling their sales with the CD, what is your explanation that Nintendo having all advantages during SNES weren't able to significantly outsell Sega and why do you think the Europe and RotW would become much bigger sales to Nintendo? They simply didn't go there when they had Strong NES, competitive SNES and loser N64 so why in the alternate history would they also start caring?
I think we're putting too much of the value on the company and not the content. Some people are loyal to a brand but most just want the best content. There's been BS comments in the past l like "Xbox 360 just sells in North America because it's an American console" but no. People but the best product. The Genesis launched in 1989 in North America and it was obviously superior to the NES. It had the market to itself for over a year, unchallenged. Even when the SNES launched, the Genesis appeared to be the better product for a long time and up until the end got better versions of many multiplats. The thing is, Nintendo supported the SNES longer when it felt like Sega had already moved on. Their focus shifted to Sega CD to 32-X to Saturn. They quit being competitive. When you compare SNES and Genesis you have to keep in mind that you're comparing a console that seemed to quit fighting halfway through the battle---a lot like Xbox seems to do against PlayStation.
Again, using North America because I know nothing of Europe, the PS2 was the most successful console of all time. Everyone had one. How did it go from being so dominant to being outsold so handily in North America? Why did people suddenly start caring about the Xbox brand? And why did they suddenly go back to PlayStation a generation later? Same with Nintendo time and again. The name on the box matters much less than what the box has to offer.
If the N64 was able to offer a better experience than the PS1 (and being twice as powerful that would be a given) for the same price, that would be a given. Side by side, I think a lot of people would agree that Nintendo's first party content was overall superior to Sony during the 5th gen. Third parties won the battle for PlayStation the same way they made Xbox 360 a contender and the same way they made PS4 such a beast (though I will gladly admit that Sony really stepped up their first party game during the PS3 era and much of the PS2's lifespan). The N64's cartridge format just created obstacle after obstacle for developers.