I am mostly from the Windows world, from running Windows 2.04 to Windows 10 today, my entire working life has been Windows. And the only uniform things about Windows thorughout that time is that is that it is crappy, and that Microsoft will find a way to screw up anything that should (most of the time, accidentally) work well.
All that being said, if the new AS Macs turn out to be really, really, good, the PC industry will react. When vendors like HP, Dell, Lenovo, etc. start to see sales dropping off significantly, they will start to look at ARM based designs of their own, just to try to either regain the lost market share, or to prevent any future erosion of their profits. Either way, it will put pressure on Microsoft to come up with a "good" version of Windows on ARM. An x85-x64 emulator will be part of that. So running x86-x64 Windows apps will be possible.
Windows on AS is not a technical issue; it is a licensing issue, and is supposedly under discussion between Apple and Microsoft right now, if Rene Ritchie is to be believed. I don't think that Apple would even be talking to Microsoft if Windows apps had no possibility of running on AS Macs. I realize that this is probably part of a massive discussion between Apple and Microsoft on a number of things, including the X Box Game service onto the iPhone App Store, getting Office 365 running natively on AS Macs, etc., but it is in there. If there is an x86-x64 emulator running (probably crawling would be a better description) on a Raspberry Pi under ARM Windows, it isn't a far reach to see the same for an AS Mac with a VM running ARM Windows doing the same. Microsoft could easily license that emulator, and bring it into a customized version of ARM Windows made for AS Macs. Microsoft has a little history of doing things like that. They built an Intel emulator back in the day of the 68K Macs for the Mac version of Office. Instead of re-writing the code for Office to run on a 68K CPU, they wrote an Intel emulator for the 68K, and used the same code for the Windows and Mac versions. So none of this would be new to Microsoft. And it is in Microsoft's best interest to do so; they would sell enough Windows copies to make it worthwhile, I think.