The DRM thing is a sword that cuts
every direction. The only viable option I see is to buy content only in formats I can convert (nice for me that I like the stuff Baen publishes, but there are ... other options too). Presently, I'm only buying formats I can't convert if I'm pretty sure I won't want to re-read the book later.
'Course, that strategy is sometimes hard to pull off.
I'm hopeful that .epub will have a beneficial effect on all that, but if it doesn't, then I'll continue as before.