Simmers often get bored when their sims become highly successful and their home is well appointed and there doesn't seem to be anything else to strive for. Their sims suddenly become less interesting.

Well here is a new scenario that stirs things up with a financial crisis.
Your sim suddenly finds themselves losing a lot of money.
And here is the thing, it could be bad, very bad, or devastating.

Bad: Your household items are repossessed, quite a few of them, and you have to have them replaced.
Very Bad: You owe for more than the items of your home is worth, so your sims are evicted and you have to use what you have remaining to buy a new, but modest home.
Devastating: You are near busted and all you can afford is the tiniest empty lot, or renting an apartment.
Plus you are fired from your job.

When you first start the scenario, you get a letter of phone call giving you some unsettling news.
A day or two later, you get more detail of how much trouble your sim is in. Better start making some back up plans.
A day or two after that, the hammer comes down and your sim is in deep trouble.

What forms these take is up to EA to decide, but add your ideas.
I would like these to be related to whatever job the sims have, or whatever scandal a sim has gotten into with chance cards
It would be cool if your sims past history has something to do with what happens to them.

Perhaps this is a ticking time bomb scenario that just sits there, waiting for your sim to get a bad chance card, or bad reputation.
That might be too complex for TS4 scenarios, but it would certainly be more immersive.

The scenario ends when your sim has the financial setback. The simmer then role-plays the fallout.
Do your sims get divorced? Do the kids turn to a dark path? Do they pull together and make their climb back to the top?
Or do they just settle for the simple life?