I have no idea how feasible any of it is, but maybe different feeds for reading lists and reblogs? So the content you opted into by subscribing to someone is separate from the reblogs you didn't opt into. The reblogged content has its own page and is easily browseable to promote discovery, but isn't plonked into your reading list -- if you don't want it there. Flexibility like being able to direct reblogs with specific tags or by specific users onto your reading list, or merge them completely, would be pretty cool.