These types of lures in advertising can be referred to as "come-ons", as defined (#1) by MW-O:
Full Definition of come–on:
1: something (as an advertising promotion) intended to entice or allure
2: a usually sexual advance
A great example of a come-on that boosted interest and sales for DC Comics is described in Geoff Williams' article in Entrepreneur Magazine:
Company: D.C. Comics Year of the Stunt: 1993
The Stunt: Whether we're talking art or not, D.C. Comics is--yes--a
business, generating approximately $40 billion in revenue each year.
So it's not surprising that many people felt that releasing a comic
book called The Death of Superman was a marketing stunt, given that
nobody with half a brain really, truly thought this company was going
to stop producing its most popular title, a hit since the Superman
character was born in 1938. (According to a recent estimate published
in Entertainment Weekly, since that time, Superman has generated some
$4 billion in revenue.)
What Happened Next: The news media covered this development
extensively, not quite as if a head of state had passed away, but
seriously enough, and the comic book featuring his death sold out on
the first day. As more issues were published, they kept selling out.
In fact, millions of readers purchased not just The Death of Superman
issue but numerous others that followed, including Funeral for a
Friend and eventually--who would have guessed?--The Return of
Superman.
Lesson Learned: If you have a popular product but feel that sales are
stagnant or your customers' excitement toward the brand is weaning, it
may not be a bad idea to tinker with it. "Well, not so fast," you're
probably thinking. "Jump into a time machine and see how people felt
about New Coke in 1985." But that wasn't a marketing stunt--it was a
colossal business mistake that offered numerous marketing challenges,
which Coke eventually conquered, by reverting back to its original
formula. Businesses revamp their products all the time, whether it's
coming out with a "new and improved" formula that truly is new and
improved (unlike Coca-Cola's 1985 misfire). But more often than not,
instead of replacing the product, companies now just add new varieties
to their line. What Superman and other beloved brands can teach us is
that if you can create some drama around your product--and tug at your
consumers' emotions--you may just find that your potential for
bringing in a profit is, well, super.