I just saw The Force Awakens, and it ended on a cliffhanger (literally, on a cliff).
But seriously will there be another one?
Yes. Oh god yes. We will drown in oceans of Star Wars sequels.
In the short term, Disney has plans to make a complete new trilogy:
By all accounts, these films will continue the ongoing stories of Rey, Finn, and Kylo Ren.
There are also longer-term plans for a trilogy of Anthology films, set in the Star Wars universe but not part of the ongoing story of the new trilogy:
After this, preliminary talks at Disney could see a further fifteen years worth of Star Wars.
If this seems excessive, recall that, at time of writing, The Force Awakens is the highest-grossing domestic film of all time1, leading Avatar by $155 million, and the third-highest-grossing film worldwide, trailing Titanic by a paltry $120 million and Avatar by $720 million.
Unless and until the movies bomb spectacularly2, Disney's investors would revolt if they didn't keep churning out Star Wars movies
1 That's not adjusted for inflation; if you adjust, then Gone With the Wind still wins handily, with The Force Awakens trailing in 11th place, which is still indescribably impressive
2 Which seems unlikely, at least in the short-term; The Phantom Menace is the 7th highest-domestic-grossing film of all time ($474 million unadjusted), while Revenge of the Sith is 25th ($380 million). The lowest of the franchise is actually Empire Strikes Back, at 66th ($290 million). Even when they're crap, Star Wars makes bank
Short answer: yes, there will be at least one sequel trilogy (episode 7,8,9) as well as non-trilogy related films that focus on other events and characters outside the main story ('Rogue One' is currently in production and details events prior to Episode 4)
The trilogy is comprised of the forthcoming Star Wars: Episode VII The Force Awakens, directed by J.J. Abrams and written by Abrams and Lawrence Kasdan for a release on December 18, 2015; Star Wars: Episode VIII, written and directed by Rian Johnson; and Star Wars: Episode IX, which Johnson is writing a story treatment for.
More details are here if of interest:
The official title for Star Wars Episode VIII is The Last Jedi
According to this article, yes, and it is already in production:
in late October, just as the world was starting to wonder about the whereabouts of Luke Skywalker, the guy who plays him was sitting at a table in his tree-lined Malibu yard, wearing Batman-themed Converse sneakers. Hamill was just starting to regrow his Jedi beard for the follow-up, Episode VIII — which would soon need him on set.