The companies that directly compete with Nvidia (AMD & Intel) are not ARM customers. ARM's biggest customers are mobile phones, which could benefit from an Nvidia GPU
Until now the competing products of NVIDIA and Qualcomm differed in NVIDIA having worse CPUs and better GPUs and Qualcomm having better (ARM-designed) CPUs and worse GPUs.
I do not find it believable that in the future NVIDIA would ever provide Qualcomm with better CPUs than those of NVIDIA products.
Given NVIDIA's desire of dominating the datacenters, it is also hard to believe that they will give to all other companies who will attempt to design server CPUs new ARM cores at the same time when they will be available for the internal NVIDIA design teams.
ARM does not make CPUs (it makes CPU IP), Qualcomm does.
The fact that NVIDIA builds bad ARM CPUs does not change with the acquisition as far as I can tell.
For that NVIDIA would need to invest a lot of R&D into their CPU team, and again, if it does that, it can compete with Qualcomm, independently of whether the acquisition takes place.
I think the overall trend is still accurate and in either case ARM + Nvidia is (or would be) a compelling provider of hardware but the segment of the market that needs/relies on X86 architecture does seem to be shrinking.