While a move to Arm promises users with lighter and more efficient PC hardware, the state of PC gaming on Arm has a lot of catching up to do as the developer ecosystem remains in infancy.
It's in a state similar to Linux gaming, it depends on the game. It's potential is making Intel and AMD sweat, though. AMD is already designing ARM CPUs, but so is NVIDIA. It could be very good ... or very bad if they attempt to embrace, extend, and exploit with their own chips.
ARM gaming doesn't end well for ARM either. RISC-V is creeping up on their embedded market, and gradually appearing in dork-oriented laptops and twee low-end desktops.