I swear I’m not trying to be difficult or antagonistic. I feel like I’m wasting your time, and that really wasnt my intent. 
Simple real-world example. I want to update Fontawesome from v5 to v5 Pro, but its only offered as an NPM private repository (since its not worth it for them to create one for bower). That’s not reason enough to do a full redevelop of my theme.
Similarly, my theme has 3 other dependencies with small security vulnerabilities, but the devs are no longer providing bower repos. And the trend of non-git dependencies that have no bower repo is going to keep growing.
And its (theoretically) a lot faster to move the bower dependencies over to NPM so I can continue to update them, then it is to completely rewrite the theme from the scratch. Lucky for me, @KimH outlined how she did it, so I’m going to take a stab. All is good in the world 
Correct. While Sage 9 was exciting when it launched, I havnt had any real free time to play around with it. Then I ran into this bower issue, started doing research on how to migrate to NPM, and saw your comment from January that people who want to use NPM need to switch to Sage 9.
So, I started looking over the documentation (trying to grok the new folder structure, build process, blade templates and controllers, and searching the forum/stackexchange/github to see if there was an easier way to make the transition to v9. Meanwhile you responded to my post.
From the announcement post: “Currently, you can opt-out of Blade templates by replacing them with regular PHP ones (you could copy over the templates from Sage 8 if you really wanted to).”
This is the part I was stuck on (and would have been a new thread, if you/kim hadnt responded here).
Does this mean pasting my old templates into .blade.php files, and including whatever thing is needed to route it through the @layouts or controller.php (as implied in the forums ) and if so what needs to be left in tact, or can I literally delete the blade templates, and copy over my old ones into resources/views? Would I still need the app.blade.php file or can I delete that one too? Where do I put all my base-custom.php files in the new hierarchy? What do I do about the wrapper - will blade’s template inheritence work in its place or do I need to import my sage 8 wrapper, and if so to where?
So yeah, the announcement says you can use PHP instead of blade, but nowhere in the docs does it say ‘how’.