It's not known if Nova Covert Ops's three new missions will be paid DLC or a free download.
At Blizzard's Future of StarCraft panel during this year's BlizzCon, Blizzard laid out its future plans for StarCraft II now that Legacy of The Void is almost upon us. No additional expansions were revealed, but Blizzard plans to continue to support the game with "Mission Packs" - the first of which: Nova Covert Ops will be released sometime in Spring, 2016.
Nova Covert Ops is a series of nine missions, delivered in three episodic installments that take place after the events of Legacy of the Void. The story focuses on Nova and her involvement with a group of Terran separatists known as the "Defenders of Man," and just like in Kerrigan's Heart of The Storm missions, Nova will be directly controlled in each mission.
It's unknown how much Nova Covert Ops will cost, or whether it will be a free download like the Legacy of The Void prologue missions, as all Blizzard said on the matter was to "stay tuned for more information including dates and pricing."
As for what may come after the Nova pack, Legacy of the Void Lead Designer Jason Huck said the team wants to see how fans react to the new pack first. "We didn't want people waiting two years for the next thing," he said, adding that the pack will have full cutscenes and voice over. "The packs will be tied together seamlessly if you end up playing through all nine missions together, but we will probably end the 3-mission installments on a cliffhanger."