Aggregations of various sorts are being produced by publishers, sometimes working with scholars and/or libraries:
Electronic facsimile editions (digital surrogates for out of print, brittle, or rare materials) are also being produced by libraries:
And one or two University Presses are even willing to handle them:
In the long run, will such editions end up being library-published? author-published? press-published? Hard to say, but since they meet a need, and since they don't duplicate the functionality of print, they will probably continue to be produced, by one or more of these.