There's been a recent conversation about VHS-only film titles jump-started by Anthony Kaufman's article on the death of the format. My favorite quote:
As the entertainment industry focuses on improvements in quality, in the move from DVD to Blu-ray, for example, cinephiles will ironically face increasingly restricted viewing options, because the technology requires pristine 35mm negatives.
The whole article is worth reading (apparently, the cost of digitization is $30,000 per film), as is Peter Martin's post. I can reiterate that the issue has been particularly pressing for me as I go through my 1947 project. Mind you, not even half of the titles I'm considering got an official studio video release in any format. Out of about 230 titles, only 45 have official DVD releases; on top of that, I was able to find official studio VHS releases for about a dozen additional titles.