I'll make this simple instead of praising the things we can do I'll ask what Can't you do on your iPad Pro that limits you to still need a PC or Mac?
Thanks for the question, hopefully someone from Apple will read this.
I am an author, I write, correct and edit a lot of documents. Corrections without a mouse are really difficult and an additional keyboard is always a must (though I always buy that for my iPad.)
I need to do a lot of research and formatting, I do need several programs quickly with instant access. Again it is the access method, but it is also the windows that I have on my mac that are simply faster. The iPad just takes too much time. (Esp. when they change the swipes, swips and swops again, so that I keep forgetting which "shortcut" I should be using in this currecnt software / hardware installment.)
I need to edit lots of pictures, quickly and insert them quickly in my documents. I am simply a lot faster on a desktop machine than on an iPad.
Apart from that I am a music buff, I own a l-o-t of music, it is already a pain with iTunes on the mac, imagine that on an iPad. I will not give up my music collection in favour of Apple Music, I want to remain in control of my music, my playlists and the things I own.
Which finally leads me to the point that I am growing evermore suspicious of all things online. It might be my age.
And then there's my backup system. All in the cloud: nice and fine. Seven backups: finer.
For me the main problem is speed. I will not go for a MS Surface, I will stick to my iPad but in the foreseeable future, I do not see me working solely on an iPad, though I'd love that.
Thanks!
Alex.