Cartridges were only 1 of the mistakes Nintendo did with the N64.
Their stubbornness regarding controll over third parties, allowing only selected ones to develop for their console, caused a lot of damage too.
The battle would have been a lot closer, yes, but I don't know if Nintendo would have won.
Please excuse my bad English.
Currently gaming on a PC with an i5-4670k@stock (for now), 16Gb RAM 1600 MHz and a GTX 1070
Steam / Live / NNID : jonxiquet Add me if you want, but I'm a single player gamer.