well, i do think the legendary weapon and speeder are nice ideas, but i think that they should be rewards from legendary quests that are made available by reaching certain legacy levels.
when the quests are unlocked, you have to get the quests from a certain spot, and finish up the multitude of epic quest phases to get the quest done, then hand it in and presto, legendary item/pet/speeder.
this way they can implement a legendary while keeping the experience of getting said legendary an epicaly legendary experience, all the while keeping legacy levels relevant.