I personally think it's a mistake for any author to sign away e-book or print-on-demand rights without some kind of strict time and/or sales-figure limitation. Otherwise, the publisher will be able to make the claim that the book remains in print, and rights will quite literally never revert to the author--even if the publisher never sells another copy, physical or digital, of the book. It's unconscionable for publishers to try and trick or browbeat their authors into giving away such rights.
A strong writers union would help here. But, for so many reasons, that's just not going to happen. Writers, remember: the publisher is not your friend. The publisher is your enemy. You may make a truce, enter into detente, even temporary alliance -- but do not forget that they view their interests as distinct from yours, and they will fuck you over when it suits them to do so.