Inquiry of the Dragonslayers

Meta pick Mid lane Dragonslayer:

Riot, will you create a mid lane Dragonslayer simply because there isn't one yet, or will you continue (if you do) the Dragonslayer line according to how you want to?

In regard to the lore of being a Dragonslayer:

So far we have 2 Demacians, 1 Targonite, and 1 Freljordian.

All of which portray a "good guy" vibe according to their lore.

With this being said, does that mean any Noxus/Shadow Isle/Bilgewater/Void champs are ineligible for the Dragonslayer title?

Color scheme of the Dragonslayers:

Vayne, being the only female slayer so far, has blue Dragonslayer armor. Jarvan IV, Braum, and Pantheon all have reddish-orange armor. (Pantheon with a mauve-esque cape)

Is this because Vayne is a girl or is this because Vayne slew a different type of dragon? (The summoner's rift pre-visual upgrade dragon was blue. The current one is red orange. Does this mean the two dragons are different?)

** Dragonslayer eligibility**:

All champions on the rift have slain their fair share of dragons. To be a Dragonslayer, did the Champions have to kill their Dragon PRIOR to joining the League, or do they earn their title simply by slaying a select amount of dragons.

(Disclaimer: With the 6th addition to the Blood Moon line, I recognize that adding a mid lane Dragonslayer doesn't mean the collection is complete.)