Also, you forgot to mention the Clone thing - You can "Clone" your own legendary creature and not lose either one. For example, if I have a Geist of Saint Traft in play, then cast Phantasmal Image as a Geist of Saint Traft, I have two Geists of Saint Traft in play and get to keep both. This has large impacts on Commander especially.
Wrong. The new rule prevents auto-destruct of a legend or PW of the same name if
someone else casts one or copies. If you cast another of the same legendary or clone it, you have to trash one. This is addressed specifically and without doubt in the mother ship write-up (e.g., if someone pacifies your Olivia, you can clone her and bin the pacified one rather than lose both). You
cannot under any circumstances control more than one of a given legend--period.
For the most part, this rule just means that everyone gets to play their deck as built and that legends can't be hated out with clones. It's another step by Wizards to make the new and casual player more "happy" with the game. It has also been speculated that this is being done to facilitate the Theros block, which is expected to be very legend-heavy. This would make sense, as starting the new rule with M14 gives everyone a chance to settle into it before Theros goes live.
The only real problem creature I see between the the time of the new rule activation and rotation is Olivia. By nature of her stealing ability, whoever gets an Olivia on the field first blocks anyone else from playing her unless they kill the initial Olivia first. Assuming that most sensible people are going to have 6 mana before casting Olivia, if someone else drops their own Olivia, the original Olivia can just steal and thereby kill the
opposition under the new rule. Other legends will simply achieve parity through the new rule.
