The biggest question here is does apple care about gaming enough to challenge Nvidia / AMD / ?Intel? ?
Hardware is only part of the challenge on gaming GPU performance. NVidia and AMD spend huge sums of money working with developers to have code implemented to run efficiently on their GPUs. This isn't something I would be expecting from Apple. This is a big part of the performance delta between raw performance and game performance demonstrated. NVidia and AMD invest massively in their drivers optimizing games to achieve the higher level of performance. This is not something I can easily imagine Apple doing.
Funnily enough I would think Apple would be in the perfect place to make a play at Gaming if they were willing to invest the time and money. With the inhouse silicon, app store, distribution, money and brand. Everything except the culture and people. They could create a SOC with both reasonable compute and GPU and package it up in a Game console version of the Apple TV. They would likely be able to share costs across other product ranges, leading to better margins. They have the money to help with marketing and with their brand presence, they likely wouldn't actually have to spend much to get there.
