Anyone who insists they know how the landscape will look in 20 years is a fool.
That said....
I have no idea what specific organizations will be around. However, I suspect that in many ways, things will look fairly similar to they way they are now: a handful of big publishers and big retailers, and a diversity of smaller organizations, with most of the public buying big hits. AFAIK this is the way it has been for decades. For example, smaller specialty music labels like Stax, Motown, Chess, Nonesuch, Impulse and so forth were doing business whilst giants like Warner, EMI, Columbia were much larger.
And
big hits aren't getting killed by the Internet. Apparently both the blockbusters and the "long tail" (obscure low-selling titles) are doing better, and mid-range titles are losing out.
Anyway, the reality is that the overwhelming number of writers simply cannot or will not want to write, edit, proofread, format, promote, market, retail, shop movie rights and manage their works single-handed -- especially those who aspire to "blockbuster" status. For example, as distribution costs fall, more books written by amateurs and aspiring pros will be published; getting noticed amidst that froth will become increasingly difficult. So while ebooks will likely cut out one intermediary (namely, book distributors), there will always be a role for publishers and retailers.
And of course, what works well for Baen will not necessarily work for larger or different organizations. Baen has a specific genre and an existing brand identity, and as such they (and similar organizations like Harlequin or O'Reilly) have better options for side-stepping retailers and thus reducing costs. However, they still lose sales opportunities by not being on the "virtual shelves" and getting tagged with the "if you like X, try Y" recommendation engines, for example. More critically, this approach won't work if the publisher wants to publish a diverse range of books, and thus cannot build much of a brand identity.
So while I do not know how the future will work, I find the idea that "Baen is a blueprint for the future" has a limited utility.