Critical missions – the thrust of the main story and each individual planet’s story – will be marked with different icons and will be the only missions shown by default. If you want to explore a planet in more depth, you can opt to see the Exploratory missions offered on every planet, with the planetary level sync ensuring that you never wind up too far above the planet’s power level. Heroic missions are also being restructured to two-person affairs available via a weekly console; check out the full diary for details.
Star Wars: The Old Republic‘s upcoming expansion is very much focused around stories, it’d be a bit odd if all of the old missions went away entirely. At the same time, the path through planets was pretty bloated and not always very story-focused. A new development diary outlines the changes coming to the core worlds and the renewed emphasis on story progression, making the most critical storyline missions the focal point for players moving through planets and class stories.
Source: Official Site