As mentioned earlier, Intel bringing their own fab capacity into the fray can potentially change the game massively.
Except that - at least initially - aren't all their - Xe descrete GPUs going to made at TSMC potentiality eating into AMD's and Nvidia's supplies?
There even talk of Intel deliberately buying up TSMC capacity to deny it to their rivals although TSMC are probably aware of that and hopefully see Intel as a short-term costumer and will treat their queue position accordingly (unless some American protectionism comes into play and TSMC is forced to prioritize Intel).
As for drivers... Well it is true that Intel have been making iGPUs for ages, but their driver reputation there is pretty bad. Stable drivers at running Windows, with very little game optimisations.
People perhaps underestimate the work required for gaming drivers. Often the driver team has to rewrite the whole shaders for a game (possible a bigger problem for AMD when Gamework titles comes out possible deliberately written to perform poorly on Radeon and they have to rewrite whatever they can without access to the source, but I'm sure occasionally Nvidia are also challenged with an AMD sponsored game).
Unless Intel are willing and able to throw vast resources at drivers, they will lag behind sometimes massively so. And if Nvidia perceives then as a big thread, I'm sure they'll play nasty. AMD possibly too although rather than sponsorship they seem to rely mostly on riding of the back of console optimisations.