So what does it mean for ARM µC's? shall I just go off and learn some other chip series?
Nothing. If nVidia is to jeopardize the ARM MCU market, do you think your UK government will let it happen and f* all UK engineers? Unless ARM says f* off UK market, UK government has the rights to vote.
In the short term I expect no changes, especially for microcontrollers.
In the long run though I expect nvidia to drop there ARM branding altogether, and fire/relocate the UK team as soon as they can wiggle themselves out of the UK government protection clauses.
I expect them to stop selling the IP for the A series of cores and start doing their own silicon, much better than anything else other parties have to offer (by giving other people the specs for the next architectures at the last minute for example), Quickly becoming the dominant player in the Android space (maybe aided by selling at a loss at first, undercutting the competition). This will almost certainly push Qualcomm out of the mobile processors market, and probably Samsung as well. Once they have a solid lead in market share( 80%+) they will start jacking up the prices significantly (as they did with GPUs) so I expect prices of phones to raise significantly as a result.
In the server market they will come out with their own chips, they will also stop licensing stuff to other companies in that space, or if they legally can’t (unlikely) thy will jack license prices up so much (shkreli stile) that they will drop out of the race
Amazon, apple and other similar size companies will probably not be affected, as I assume their legal department will have gone over everything in the contract with an extremely fine toothed comb, making sure they can continue to use and develop aarch64 autonomously.
The microcontroller space will ignored at first, in the long run I see two scenarios, best case nvidia will keep operating as ARM is now so they are able to pretend to support competition, market and all of that if the antitrust authorities wake up to the shady anticompetitive practices they have been pulling for decades. The second, frankly more probable scenario is that they will abandon the segment and stop developing new cores, as there just isn’t enough money to be made (the margins on MCUs are way to low for an nvidia style company). That said the current offer is probably more than good enough for the foreseeable future in terms of pure MCUs. For the more IoT/edge computing use cases where a little more grunt is necessary I guess RISCV could fill the gap, if nvidia doesn’t decide to compete