Yeah, that's an interesting take. There's a little more to it, the business model is frail.
Comic Books (floppies, not digital editions or graphic novels) have been sold exclusively through comic book stores since the 1990s. Diamond is the single distributor who services all comic book shops.
Most comic book shops have been seeing declining revenues for a while now. Go into one, chances are new comics are going to account for the smallest amount of shelf space. Magnets, figurines, t-shirts, posters, back issues and other stuff make up the majority of sales at comic book shops. To give you a sense of how the industry has contracted, there were about 4,000 comic book shops in the North America and Europe in 2014, in 2012 there are about 1,800. And people are not moving to digital, digital accounts for about 10% of total comic sales.
The risk is to the distribution model, there may not be shops when this is all over. For the Publisher -> Distributor -> Retail model to work, shops need to make big enough margins to weather a bad month or two. The problem is they have been having bad years, many owners are not in a financial position to deal with the lost sales over this period.
Without the shops, there's no one to distribute to. Without the distributor, the publishers have to find new ways to get their comics into the hands of consumers. This creates problems. On the one hand, consumer behavior does not change overnight, sales channels take time to develop.
On the other hand, independent publishers - not Marvel and not DC - will need to work out deals with other distributors to get into places that will sell their comics. The beauty of Diamond was they would deal with anyone. That's not true of other publishers, some of who won't deal with small-volume publishers.
To answer the question, how much will coronavirus damage comic books - small publishers will suffer greatly, anyone without a large existing audience is probably out of business. The Big 2 will cut their lines down to 40 titles a month, there just won't be enough shelf space to support a larger set of comics. A lot of comic book shops are already out of business, so they will need to find new places to sell their books. It remains to be seen if consumers will transition to buying comics at Walmart / Target / supermarkets.
A secondary effect of all the comic book shop closures is backissues. Many shops make their margins on backissue sales on the Internet. Going out of business means there's going to be an excess of supply, as retailers take over each other's catalogs. This is going to drive down prices on eBay, which will be the final nail in the coffin for a lot of comic book shops. So expect to see another round of closures starting around November.
A tertiary effect of comic book shop closures is an excess of talent. There are a lot of creatives working in comics, artists mostly get paid by the page. There's going to be price competition for very talented artists accustomed to making a (relatively) high page rate, the people who stay in the industry will need to adjust to lower rates. Compensation has always been incentivized, where artists make more for creating books that sell more. Expect to see a lot more of that going forward, maybe the average page rate for a penciller will be around $200 with a nickel for each copy sold over 40,000.
The problem is no one has any money. Comics may be a billion dollar industry, but that's because they've been increasing prices, not circulation. Marvel and DC are going to run into some challenges moving into a boutique retailer model simply because the Walmarts of the world want to sell mass-market publications. They're not going to make the same margins they made with Diamond, not sure anyone wants to be paying $10+ for their comics. So there's a limit to how well the industry can scale back up to pre-covid-19 levels.