I don't know if Nvidia is eager to re-enter the SoC market. It wouldn't be a clear path to more money, since they would need to then handle modem, wifi, ISP, display, etc... instead of just CPU & GPU. And they'd need to work with Android & its HALs. And all the dozens/hundreds of device OEMs.
They could, but that's more than just an easy money grab. Something Nvidia would already be familiar with from Tegra.
What seems more likely/risky would be nvidia starts charging a premium for a Mali replacement, or begins sandbagging Mali on the lower end of things. But Qualcomm already has Adreno to defend against that.
They released a new SBC aimed at autonomous vehicles. They haven't had a mobile SoC since 2015's Tegra X1. Which only made it into the Pixel C tablet, Nintendo Shield, and Nvidia's Shield TV (including the 2019 refresh)
They could, but that's more than just an easy money grab. Something Nvidia would already be familiar with from Tegra.
What seems more likely/risky would be nvidia starts charging a premium for a Mali replacement, or begins sandbagging Mali on the lower end of things. But Qualcomm already has Adreno to defend against that.