Why? Not wanting to get off topic, but why do users need to go back more than a couple of days and edit their post? As you stated, anything beyond 14 days is usually forgotten about, so why such a long time frame? I’m fairly certain we only permit 1-2 days on ours.
Back on topic:
I too think it would be a good idea to deal with affiliate links. I’m not sure it is “core” material, but the plugin looked promising and you could add new URLs as you saw fit (granted, it would be nice if those URLs could be added in the admin area).