http://www.msn.com/en-us/movies/news/carrie-fisher-completed-work-on-‘star-wars-episode-viii’-before-her-death/ar-BBxCPQZ?li=BBmkt5R&ocid=spartandhp
Here's your answer.

trilogy? They passed "trilogy" a long time ago.

Read her autobiography. She was a heavy cocaine abuser and cocaine (more severely than cigarette smoking) can damage your aorta and heart valves during your early years only to come back as you age because when all humans begin to age, the heart is one of the most fragile organs that can exhibit repercussions from past abuses. Even though Carrie showed resilience and kicked her cocaine addiction she also struggled with alcohol which is another toxin that can adversely affect your heart condition.
I haven't read anything about it, but I always thought that her speech impediment was due to a stroke because I have relatives who have had both major and minor strokes and their speech pattern deteriorated much in the same way Carrie's had.

She had a weight problem, although she lost a lot of pounds fairly recently. That could have something to do with it.

Though it's certainly not unheard-of, for a 60-year-old seemingly healthy woman to suddenly suffer a massive and fatal heart attack seems unusual.
I wonder if there were some underlying health issues, undiscovered or not thought to be serious, at work? Carrie was well past her druggie days and a heart attack just doesn't come about for no reason. Sad and shocking.
But the series will go on, if that matters.

I thought she was going to get through it.

Dammit OP your wish just came true RIP Carrie Fisher.
End of line

The series will continue no matter what. This is a for profit business.
Actors have passed away in the
middle
of films being shot, and the film continued to completion with success. The best example may be Natalie Wood dying almost in the middle of filming Brainstorm. By using creative re-writing, picking up footage from the cutting room floor, body doubles, and voice doubles, they finished the film and made it all work pretty well.
Because Episode IX hasn't been shot yet, I imagine if she did pass away, or were too ill to continue, they'd write her out of it as well as possible, or just use other footage or archival footage to explain it away. Because it sounds like her heart attack was fairly serious, they may already be planning on re-working the script to cut her role back, or find a way to make it as easy as posible for her to shoot when the time comes.

if Miss Fisher dies, then they can cast Amy Shumer.
I swear if you compare their faces they look related. Of course, Amy would have to drop her faux-feminist tone, some weight, and dye her hair brown but I think it could work.

I'd bet my bottom dollar Disney would not recast Leia for Episode IX-C.
If Leia survives VIII, and Carrie died before IX or a future film begins filming/during filming/whatever, Disney could:
A. Between films, have Leia die in battle.
B. Briefly show Leia (archive footage/CGI/stand-in) and then kill her in battle.
C. Briefly show Leia, and have her "walk off into the sunset"/board a ship to live happily ever after.
D. Between films, have Leia "walk off into the sunset" to live happily ever.
E. ?
F. ?

Many characters have died in the series - along with some of the actors - so the series can survive a character dying. The death of an actor/actress might require a rewrite of one of the movies.
As happened in the Harry Potter movies, the death of Dumbledoor's original actor didn't force them to stop the series. They had another actor take over that part. It's conceivable they'd do that with Leia - not likely, but possible.

Of course it won't. They'll figure out a way to explain her absence.
And Carrie does seem to be in a stable condition in hospital

Carrie has already finished filming Star Wars, Episode VIII, but if she died, is unable or doesn't want to do Episode IX, then she would probably just be written out of it completely or the character could be killed off.
With all the money Disney paid for the Star Wars franchise, there is no way they would just stop making new movies.
I don't know what they have to say. It makes no difference anyway. Whatever it is, I'm against it.

If Daniel Craig died, would James Bond continue without him?

Do you think the new Star Wars trilogy is canceled because of Fisher's heart attack? Is it possible she could pass on?
Regarding your first question: No. The money is too big and Carrie, to be blunt, is incidental to it.
Regarding your second question: It's more than "possible" she'll pass on. It's a 100% certainty just as it's 100% certain that you, me and every other human being will "pass on". What you mean is, will she pass on from her recent heart attack. I have no idea. Why don't you contact her family and ask for an update?
Regarding your post overall: Pretty stupid and tasteless. And it's "If", not "Is".