I think the argument for 128-bits being necessary strictly for routing memory in a single "computer" is fairly weak. We're already seeing the plateauing of memo

I think the argument for 128-bits being necessary strictly for routing memory in a single "computer" is fairly weak. We're already seeing the plateauing of memory sizes nowadays; what was exponentially in reach within just a couple of decades exponentially recedes from us as our progress goes from exponential to polynomial. But the argument that we need more than 64 bit capability for a lot of other reasons in conjunction with memory addressability is I think very strong. A lot of very powerful and safe techniques become available if we can tag pointers with more than a bit squeezed out here and a bit squeezed out there. I could even see hard-coding the CPU to, say, look at 80 bits as an address and then us the remaining 48 for tagging of various sorts. There's precedent, and 80 bits is an awful lot of addressible memory; that's a septillion+ addressible bytes, by the time we need more than that, if we do, our future selves can deal with that. (It is good to look ahead a decade or two and make reasonable preparations, as this article does; it is hubris to start trying to look ahead 50 years or a century.)