"In case you haven't noticed, software development and maintenance is never-ending..."
There arrives a time when a software package does exactly what it needs to do, and any new features are either unnecessary, provide for needs of an ever-decreasing subset of users, or are even backward steps in usability or functionality, just for the sake of being different and new.
The reality is, MS Office reached this stage somewhere around 2007 / 2010 (some would argue even earlier), and anyone with a locally installed copy could/should continue using that for the next 50-odd years with zero problems. There is no reason why maintenance should be never-ending on a stable piece of code, because over time the number of bugs will decrease until the code is in a 'safe-enough'* state. The only reason that maintenance is never-ending is because development is never-ending, and therefore new bugs keep getting introduced. And the only reason that development is never-ending is because sales and marketing demand 'new' even when the user has no need and gets no value from the change.
*Even though complex code might never be completely 100% bug-free, it could be as close as makes no difference and/or where the effects of any bugs are unnoticeable / trivial.