I know that the Warlock's fire subclass Radiance was removed because "waiting is not gameplay", but people used it, among other reasons, because of the lack of other good warlock fire subclass.
Many quests in D1 required players to use fire abilities and the warlock fire subclass was only usefull if it was radiance (Its healing and reviving factor was also a reason). However, since Dawnblade (way of the whatever) was added, the warlock fire subclass actually got a substantial buff and it it usefull too use them for both damage and squad healing. Thus, there should be no reason for players to use exclusively radiance was it to added back in D3, especially since, if D3 was to spawn as many enemies as D2 does in some activities, Dawnblade and its "ways" would be as much if not more usefull than Radiance.
I believe, therefore, that Radience, as a "way" of the fire warlock subclass, together with the current dawnblade "ways", should be added back in D3 since the reasons to remove it are gone.
[spoiler]TLDR, I think Bungie should bring Radience back since the reason to remove it no longer exist.[/spoiler]