Morello Assures That Heimer Rework is in the (re)Works
Many champions in the League of Legends have been released that Riot has later acknowledged have some inherent issue with the way they work. In some it's a matter of having mechanics that all scale off a single stat (like Darius) who can then focus their build entirely in one area to scale to huge numbers. In others it's a matter of having a skillset that rewards coordinated teams with huge dividends while being next to useless for a team that is not well-coordinated or practiced at positioning (most notably, Karma).
Fortunately, Riot Games is not above changing the way their previously-made champions work, willing to make drastic changes for the betterment of the game as a whole, with examples of champions they've reworked being Xin Zhao, Jax, Twitch, and Evelynn.
What about the yordle?
Heimerdinger is, according to Morello, currently being reworked. The important information from his post on the forums...
* Like all reworks, some things will get better, some will get worse, some will get laterally changes (please don't expect "all skills buffed!")
* Xypherous is working on it
* No ETA yet
Don't lose hope, fans of brain-headed scientific champions! Your patron yordle will be coming back soon!