If you think about it like this, HotS is a fun game. You can play all of a grand roster and earn in-game currency to get everything you want in it. You don’t have to spend a dime. It’s a gift. Any content that comes will come in its time. Everyone wants their character in the game to make playing it more special, but if you think of new content as a gift or a surprise that could happen any amount of time from now, you can spend more time enjoying the game for what it is than being disappointed by expecting something to happen the way you want.
Personally, I would love Azshara or Lady Vashj to be introduced or WoW-themed skins for many of the heroes (like nightborne), but I can honestly say that I’ll live if they don’t show up.