You really don't own anything when you have nothing but downloads.
I don't see ebooks as a replacement for "real" books, but the readers are something useful on trips and such. Not to mention you pay through the nose for something that isn't truly yours.
Ditto for music downloads in lieu of vinyl and CDs or Netflix in place of DVDs. I don't regard them as substitutes for tangible items but supplemental.
I don't like the movement to cram these technologies down my throat. I have many "real" books that I want to keep because I have almost all nonfiction books in my collection. Plus you can't get ebooks autographed, and I have quite a few autographed books, and ebooks are worth NOTHING to collectors.
Ebooks have a place, but I will be damned if I want to be denied to right to OWN a real or hardcopy book. I fear someday only the rich will have access to hardcopy books while the peons won't have access to them at all.