a few options for Reddit: 1/ just buy Apollo. show ads 2/ do a special deal with Apollo where they somehow incorporate ads into the app 3/ API access with Reddit Premium. Apollo can now carry on as normal for premium users & charges "free" users 4/ learn to build a freaking app - people didn't end up using Apollo because of the high quality of the Reddit mobile app.
Personally I rarely use Reddit in a browser and if 3rd party apps were to go away that would be the end of Reddit for me.