Just do the math. How many possible abilities can be drawn from Heroes of the Storm? How many abilities does a WoW class need to be fully embraced, and how many have we seen that are completely new and not sourced from Heroes?
Fudge the numbers all you like, it's not going up higher than 20% tops, especially when there are plenty of HOTS abilities that we know aren't going to make it into WoW, like Alexstrasza's Dragon Form and Cleansing Flame and Chromie's Sand Blasts (Bronze is not a DPS spec). It's unlikely that Time Trap will be brought into the game either, since the functionality of that ability is designed like a Trap/Ward effect, and it doesn't look like Evoker is going to be inhabiting any of that gameplay. They look to be designed as a mobile spellcaster.
Also from what we've seen of their current abilities, many of them are completely new rather than hinging on Heroes abilities. We don't actually know if they even have Abundance; we've just seen a ground AoE heal
that looks like Abundance. Considering Green is the Healer spec, it could be a completely new ability for all we know.