IMO the more common Seferim will remain in book form due to Shabbos/Yom Tov issues. (Like Shas, S”A, Chumash etc)..And Even Shas, the more Common Meschtas will be in Book (Like Gitten, Baba Metzia), but some of the Zeraim or Taharot which are rarely learned would benefit from ebooks
however the secondary Seforim will be more on eBook formats especially with higher printing costs and frankly space issues.
Probably 90% of Learning is done from 10% of Seforim.