We've been told by Blizzard in the latest Phase 3 Preview video that players in Season of Discovery will be able to unlock Dual Talent Specialization!
When a character reaches level 40 they will be able to seek out Grendag Brightbeard, a Dwarf of Many Talents, and purchase a Dual Talent Specialization for 50 gold.
This will allow you to switch freely between two Talent loadouts without having to pay for a talent point reset.
With the flexibility of Runes being swappable at any time, this will make it a lot easier for players to flex between two different roles — or perhaps two different damage profiles for DPS classes.