The flaw here is thinking of it the same way, in the same manner, the same movements, the same metaphors, as one would think of things like Hollywood films or TV shows. But even TV is going more digital. Film has already begun moving towards the digital milieu, and you see it a lot now. That's a shift and attempt at adapting an already-existing medium. Webcomics aren't really on the same model and, as has been discussed in other posts, aren't beholden to the same gatekeeper mentality, nor are they restricted by the outmoded attitudes of the dinosaur called traditional publishing. As such, I don't really think it's the most helpful to approach the topic in that way. That said...
People know sequential art, although most have only specific exposure to the medium. Marvel and DC are decidedly mainstream and marketed for mass consumption, even in comic form. All you have to do is walk into any bookstore, and you'll see a whole section dedicated to those two and maybe, if you're lucky, publishers who aren't them too. But there are comics all over bookstores, of all kinds, from comic strip format intended mainly for humor (or commentary) to sequential art storytelling like comics, most identified with Marvel and DC in the US.
In terms of srs bzns storytelling, given, that's not usually what the mainstream has received in the past few decades. However, that's less and less so thanks to the manga boom, which helped to redefine and broaden comics as a storytelling medium. They've become a much more common part of mainstream storytelling media now, and especially with the younger generations growing into adulthood now, they're much more positively regarded...or even matter-of-factly, which is exactly what mainstream acceptance really is: the assumption of their presence as a matter of course.
Given, I was not entirely talking about the US in my original point, largely because the US isn't the be-all, end-all of the conversation or the medium. But even in the US, it's very different to how it was even a decade ago. More and more people know webcomics, or at least digital format comics, and that doesn't show any sign of decline. The dialogue is shifting steadily to a digital landscape, even in the US, where people so often seem reluctant to change and constantly hold onto things far longer than their functional viability.
Plus, my other points in my post stand.
Another point, though: I think it's honestly far beyond the capability of this subject -- and we're drifting even now -- to address what the term "professional" means. It's a word commonly bandied about in corporations and used there to bully people into dehumanizing themselves because they have no idea what the term means...and they figure those using it against them do. In fact, more times than not, professionalism is something completely missing from the corporate landscape today, and I've often said that it is a term that has effectively lost its meaning through dilution and misuse; it would be perhaps most useful if we could, en masse, reexamine it and bring it back to what professionalism really signifies. Of course, there are other factors that tie into this, such as the "puritan work ethic" and its deleterious effects on quality of life, especially in places like the US.
But that's a matter for another discussion.
I do agree, and tried to express this before, that webcomics are popular and show absolutely no sign of a decline in popularity. The struggle is more often being taken seriously as a creator, but that's not even a struggle for some. Pretty much all of it depends highly on circumstances.
