You can and should design for change, within reason, because all successful programs will need to change in ways you cannot predict
You’ve yourself here. You can not predict how it wull change. Which means that whichever design for change you’ve made, may just as well completely miss the future utilization
Which doesn’t mean that we shouldn’t design for change at all… Just saying.
It can’t not have local save data. It can delete it at exit, sure, but it needs it to load the game properly. Save game extraction might be more complex, but it is still sent to the local machine.
Unless it’s a streamed game of course.