Assuming Win10 Home/Pro:
My bet is yes they will be reinstalled.
When Windows 10 experiences a 'feature upgrade' it's essentially reinstalling Windows with an in-place upgrade. It loses settings such as the user changing the default locale and reinstates that setting however Windows 10 was first installed in this respect; I've seen this plenty of times in the UK because UK users who upgraded to Win10 with the free upgrade ended up with the US English keyboard layout even if the UK one was the default in Windows 7/8x, and then I've seen the US keyboard layout get reinstalled after a feature upgrade even though I removed it.
Also, the System Restore setting gets knocked back to the default which is super-irritating because I've built many systems with 128GB SSDs and with those the default is to switch SR off and I have to go and re-enable it, then it has been knocked off again on many occasions / customers' computers after a feature upgrade.