Notes, just an FYI if your only concern is EXTERNAL drives and their letters that's easy and not an issue even If MS doesn't correct this before it gets pushed to you

as always do Boot drive image first, then
1) unplug the USB drives,
2) then update,
3) after update replug USB drives,
4) if letters are wrong just use "Disk Management" to reassign letters the way they were.

Actually if I (or anyone with internal drives) were going to do this update, and I (we) didn't trust MS to fix it first (and they probably will, at some point - LOL) I would open PC and simply unplug all the data cables (no need to unplug power connectors) on all my drives, except obviously the boot (C drive) and pull out any extra M.2 drives (unless the only M.2 is the boot drive - leave it in) then after update simply reconnect all data cables and reinstall any extra M.2's and if drive letters wrong then like with USB drives just use Disk Management to re-map back to what I/you want

Granted users should NOT have to get this "involved" but it is what it is

Larry

Win10Pro,i9,64GB,2TBSSD+20TBHDDs,1080TI,BIAB'24,Scarlett18i8,Montage7,Fusion 8HD,QS8,Integra7,XV5080,QSR,SC-8850,SPLAT,FL21&others,Komp.14,IK suite&others, just a guitar player-AXE FX III &FM9T, FishmanTP, MIDIGuitar2, GK2/3'sw/GI20