How much "traditional downloadable software" do you have? How much other such software is sold and makes a living for those making it?
Just the music software industry alone, for example, sells about 4 billion dollars worth of VSTs, DAWs, etc every year, most of it without subscriptions.
I'm very well-versed in the field, what DAW(s) are you referring to? Cubase, Ableton, FL Studio, Logic Pro X, Bitwig, Reaper, etc. are all flat fees. Studio one has a subscription model but it's tied to access to splice assets and it's completely separate from their one time fee model.
That's the exception that proves the rule, and it's not really that popular though. They're pushing it more than there's actual update, and I think it's more for the "wanna try a music app" crowd atm (than the 'DAW using crowd'), mostly due to the limitations of the iPad.
Oh yeah, I forgot that Logic Pro iPad is a subscription. I honestly don't know who the target audience is for it. I'd think most hobbyists could probably just get away with GarageBand on the iPad which is free.
When traveling I've actually sketched out music in iPad GarageBand then brought over to my Mac and opened them directly in Logic X. It works pretty flawlessly.
Just the music software industry alone, for example, sells about 4 billion dollars worth of VSTs, DAWs, etc every year, most of it without subscriptions.