Wyrm armet, or saurian helm, both give the equivalent of HB4. Now when my wyvern is fully xp lvl'd in a zone, he will HB me for around 800 hp, without equipping any other wyvern hp+ gear. With wyv hp gear, I can get it to 1k easy. That means I can, in abyssea, get around 1/3 of my hp back every 60 seconds from my wyvern...
I doubt we will ever see another tier of HB, that is one thing that will unbalance the DRG job. If you think your HB is weak, go get some wyvern hp+ gear and buy yourself a new hat. Macro stuff in for restoring breath and you'll be a lot happier.
I'd personally like to see improved wyvern "remove" breaths for /mage - poison, blind, paralyze are fine, but I'd really like remove silence
I can see them giving us a /ja that would allow non-/mage to remove breath. making /mage pretty much redundant, but we'll see.
But yeah, some sort of quest path that modded the wyvern's model in game would be nice. Colour alone would be something, but I'd much rather he got a bit bigger