I really hope they don't bring their pisspoor Linux driver support to ARM.
I am ok with this, mostly for the reason listed above.
Given the nature of ARM, this question would be difficult to even speculate on.
Typically AFAIK it's the specific SoC manufacturers responsible for drivers, i.e. QC, Samsung, Nvidia (Tegra), Mediatek etc.
This is
one reason why Android support has been problematic in the past, getting newer driver binaries from the makers.....which makes poor support from Samsung and Exynos even more messed up IMO.
Nvidia already produces a line of ARM based SoCs, so that could be a benchmark to go by. I know that the Shield has been relatively decently supported, having just released a new upgrade. But on other devices such as Android Tablets there was poor support, except this is also common with other tablets/SoCs, so not necessarily Nvidia's fault.
One thing that would concern me about Nvidia buying ARM, would be if they try and 'pull a Qualcomm' and coerce/force manufacturers/SoC makers to have to license additional Nvidia tech, similar to Physx being 'hindered' if you didn't have a Nvidia GPU because it used the 'ancient' X87.
I would have been surprised if they didn't try to influence the ARM ISA somehow in their favour.