[bloak]

"Trivially" might be overstating it. If you do the scan at 1000 dpi and get several people to check it was done properly then very probably you will never want to refer to the original again, because a scan is much easier to consult: just turning to a particular page is much faster, and you can zoom in without having to manipulate a physical magnifying glass. But I've worked with book scans done by ordinary people using ordinary equipment and I have on many occasions found that the scan wasn't quite good enough and I've taken the trouble to check with a paper copy whether a certain short word was printed in italics or whether the exact shape of the serif can help me disambiguate a letter which was badly printed in the original (the plate wasn't properly inked or whatever). I've never personally experienced a situation in which I've said to myself, "I wish I had another copy of this same edition to compare against", but I can imagine that might happen sometimes. So I think it is worth keeping multiple copies of the same edition, if it's an "important" book, or you have some reason for suspecting that it might be important: you don't know for sure what people in the future will be interested in.

[ralferoo]

Even 1000dpi might not cut it. Remember the stories about really old texts on parchment that they discovered had been re-written on reused parchment? At certain specific wavelengths they could "see" the original text. If you just have a plain old RGB scan, that's no longer there.

More for paintings, and less so for books (except very old handwritten ones), is that the ink or paint used has its own characteristics. It might look very different from different angles due to the light reflecting off the pigment in different ways. Doesn't matter how high a resolution scan you have, it's going to be hard to scan that, and even harder to display it on a screen.