Last time, the Mac platform basically existed in isolation, thus the only problem was that apps for this platform had to be recompiled. This time, the Mac is no longer isolated - millions of developers write client- and server-side applications on Macs that are to be run on mostly x86-based servers, and their toolchain implicitly relies on the architecture being the same on dev and prod machines. That is not to say that it's impossible to change the architecture of the dev machines to something else - it's just a huge additional drawback that was not to be considered at all back then in the PowerPC->x86 transition.
These two facts tend to get downplayed or overlooked pretty frequently when it comes to the "ARM-based MacBooks" discussion, but I consider them fairly substantial and they dampen my enthusiasm for such a transition quite a lot.
There are also a lot of people only using their Macbook for presentations, text writing, or even only surfing the web. Apple's own office suit will be ported to ARM when they change their CPU architecture, Microsoft has Office for ARM available (or at least in the pipeline for 2019), and LibreOffice is available for ARM as well.
If Apple really wanted to do this, they would release their small Macbook (non-Pro) with ARM first and then describe a plan to change to ARM for the Macbook Pro line within a few years. No need for a transition period where emulation takes place, everything important is already ARM-ready. The iMac Pro is another thing, that might actually be harder but I imagine manageable if Adobe etc. are willing to invest/to be paid to support ARM.
There are of course the millions of iOS developers.
And besides that, in any conference, from C to Rust to C++ to Java, you'll see tons of Macbook-wielding developers, often the majority.
And when it comes to keynote speakers at conferences (as opposed to audience) the PC laptop is the exception as opposed to the norm...
The developers that Apple cares about.
90% of apple sales are for ARM computers, bet they'd love to only make 1 OS, would save loads of money
They are also in a position to isolate themselves again now.
