My prediction is that it will depend entirely on the future of casual computing. Will phones have adblock more accessibly 5-10 years from now? If so, that will change how apps like Webtoon operate and make money. Maybe they'll go the route of youtube and introduce subscription models (if they haven't already--they probably already have and I just haven't noticed) Will people 5-10 years from now even still use cellphones the way we know them now? All Apple needs to do is merge it with a tablet or a watch, maybe change the shape to horizontal or something and like--that would entirely change how the webtoon format works. We're basically at the mercy of whatever is going on in tech, just as we have been for the last 10 years.
So I think we'll see a push back against the apple app standard because so many people won't be able to post what they want to because of the ever changing shape of tech and the restrictions on what we can post (which will only continue to become more restrictive depending on advertisers--I mean look what happened to Youtube), and we'll go back to a lot more personal webpages and blogs of yesteryear for page format comics and also comics with content that might get censored. But, to make money doing this it'll probably be entirely through donations since I just don't think ad revenue will ever be as reliable as it once was.
As for print, I think parents and teachers are getting wise to how comics help kids with reading disabilities. There will be lots more graphic novels for middle grade, for sure--but they're always going to be held back by how expensive they are to produce. Like especially here in the States I don't see there being as many comics as there are in like Japan or anything like that, but it'll be more accepted for kids to read at school.
I think that comic stores however, are probably going to fold. I'm still surprised to see a few hanging around.