Yeah..... About that
Let's review software development cycles, shall we?
Most software is on a 18 - 24 month design cycle.
Let's assume that every software house dumps their current Mac development process so they can restart at the same time they get their hands on an ARM Mac. (which won't happen, but I am giving a best case scenario - software houses will conduct an analysis to see if the uptick in sales will justify development costs - and every last one of them will remember the hoops they had to jump through and factor in the possibility that Apple may sabotage them like they did with Carbon-64.).
Version 1 software is anywhere from 18 - 24 months out (Delivery dates - late 2020 to late 2021)- this will be a straight port - no new features. Have fun being a beta tester for every piece of software you "upgrade" to.
Version 2 - 1st truly native version with new features (Delivery dates - Mid 2021 to late 2023). All for a shrinking market.
Sure, a lot of the apps are already on iOS. They are fundamentally running on the same source code, just compiled for different targets (which Xcode and other SDEs coincidentally already does). All modern Macs (except iMac 5K and Mac Pro) already have code running on RISC, the T2 coprocessor. I'm not claiming it happens over night or even over the next few years but the ground work has been laid.
Besides, I am already a beta tester, just look at the state of Adobe Creative Cloud