> Nothing on the ARM, Qualcomm, or MediaTek roadmap is even close.
Don't count on the Mediateks of the world to spend any time on this market. Most of the licensees are focusing on high volume embedded cases where they an try to drag themselves above the commodity pricing floor by providing a package of SoC and (in my experience crappy) drivers and an android port. In fact "package" is the key word: they typically won't sell you the chip in a useful way (i.e. no data sheets) but instead want to sell you a reference board with ported software running on top.
Apple is unusual in that they have two value add products that matter and have managed to, over time, build the capability to handle it. The economic calculus for them is quite different from that of the merchant chip vendors.
There are a few possible alternatives like Qualcomm and Nvidia (!!) but the market dynamics aren't the same for them.
It is possible that an Nvidia/microsoft relationship could develop somewhat similar to the Intel/Mcrosoft partnership, but unlikely. The market is different and the regulatory environment may become different. Terminal devices (laptops, desktops, phones) aren't really where the money is any more (except for Apple, an exception on several dimensions) so the push for such a partnership is diminished.
More likely is a partnership addressing cloud datacenters between say MS or Amazon and Nvidia, but nobody is going to be willing to allow one chip vendor to have any say over their destiny. It would make sense for one of the top cloud vendors (AWS, Azure, IBM) to buy Nvidia but that would never be allowed.