The key is to keep Win10 as long as possible, shut off Windows updates, and go into Task Scheduler and delete/disable any items Windows has added that will switch to Edge and remove Explorer.
They have now made it so you cannot uninstall Edge, but then they also snuck in some Task Schedulers that run constantly. Some on my computer are running every hour and some are once a day.
They are looking for Edge updates every 12 hours and I bet one day will just wipe Explorer off your computer.
I was wondering why Edge kept updating and kept opening up when I would open Explorer.
So for those of us that lock down and disable Windows Updates, be sure to check your Task Scheduler for any updates they have hidden here.
Here where the ones that showed up in mine one day.