The unifying feature of many of the posts that insist that M4 is coming now is they all think it will be on N3E. I imagine Gurman also believes that.
Ever since Intel revealed that Lunar Lake is being produced on TSMC N3B, pretty amazing news really, the ignorance surrounding N3B ("poor yields" "too expensive") has been further exposed. Which anyone paying attention to Apple's behavior already knew, but the rumor just refused to die. It's true that N3E is designed to get better yields than N3B, but that is by design. People seem to believe that means N3B is a failure because it hasn't met expectations for yields or it has cost more than expected, neither of which is correct.
I can't say I can guess what Apple is or is not doing with the M3 Ultra, we will see, but I can say that whatever it is or is not, it's not because N3B is a failure. It's true that it is a dead end, but again, that is by design. Indeed, N3B can be seen as the peak of FinFET (FINFLEX) technology, with N3E as a step down from that summit, back onto the path toward the future, toward GAAFET (nanosheet transistors) and backside power rail. That's why the two most-advanced, most-efficient families of SoCs are using it, from two of the largest companies in the world, and by the end of this year every major OEM will feature high-end laptops with N3B silicon in them.