Another vote for 'Mammoth' here... It fits from a naming convention and trademark point of view, and also implies a big and powerful upgrade.
Completely on a whim and not at all likely but I quite like the sound of 'macOS Golden Gate' - implying a big, bold but transitional release from one architecture to the other. (Yes, I know, I'm totally over-thinking that!)
I also wonder how many more Intel Macs will be cut loose at this point - we're already seeing a lack of feature parity on Intel in favour of the ASi Macs so Apple are really pushing ahead with this. They do have precedent with this stuff; PPC Macs got the Leopard update after the Intel announcement and, er, that was it! End of the road. Heck, even the first-gen Core Duo Intel Macs, one of which I stupidly bought, were frozen out after only one update (10.6)
FWIW, I don't think they'll be *quite* so harsh this time, given the huge base of Intel Macs that are out there as compared to the number of PPC Macs in use at the time of the Intel switch. Also, the upgrade cycle for the OS was a lot slower back then. Still, we're around two years into this process now, so it's going to be interesting to see how they play it over the next few releases.
I expect Intel will still be supported for another few years but new features will increasingly be reserved for Apple Silicon, to the point where new OS releases on Intel essentially become security updates, before the plug is finally pulled.
