Maybe niche marketing of family histories and poetry, the main print self-publishing areas in the past, will be viable for enthusiasts with technical expertise and equipment, but who are not concerned with profit. Esoteric literary works seem unlikely e-successes, but maybe fans will read them on free sites. Ebooks are versatile for vision-impaired people because print sizes can be enlarged or back lighting altered. Because online bookstores are open 24 hours, you get instant delivery. Hundreds can be carried on a few portable disks in your bag.
Educators can customize e-editions for students.
However, this may have copyright implications for factual writers whose work will be more widely used for less recompense. Free sites for links may become rarer. Most ebook designs enable you to add searchable highlights and annotations to texts, so they're more versatile than oldstyle under-lining or scribbles in the margin. The Future Rights have to be sorted out. My Frequent Flyer Twins series appears to fit the international medium.