Won't most of your other users catch wind of this and fake cancel just to get the discount? And for those that don't or don't feel good about faking a cancel, you're essentially charging your happy or loyal users more. Backwards from a business practice perspective and wrong from an ethical one.
Ask a simple question, get a simple answer: no.
More elaboration:
This misconception comes from a few places.
Many HNers passionately care about money. Many customers don't. In particular, the best customers (largely businesses) perceive not even the smallest scintilla of pain from software bills ranging from $20 to $20k per month and the person who'd actually be pushing that button at the business perceives no difference in their personal lives based on what the price is.
Additionally, we live in our software, are familiar with all the intricacies, and assume that they matter. Our customers deal with our software only sporadically, and generally only allow it to distract them from things that matter to the extent it is required to accomplish their goal. They don't typically go spelunking for hidden options. They (largely) don't go to CustomersOfFooApp.com to swap hidden secrets about FooApp because customers of FooApp care about FooApp about 1/10000000th as much as the developers of FooApp do.
Finally, most people have what you might describe as either a moral compass or a fear of embarrassment which will counsel them that attempting to scam businesses for discounts is not something they want to be doing. (This assumes you're not dealing with a customer population which is toxic by nature. Charge more.)
Some gamers speculate on the frequency at which the service allows this.
I've used this to my client's advantage by seeding coupon sites with special coupons. They don't get much of a better deal than anyone who sees other promotions on the site, but you can trick them into spending more money with minimums.
On the second half, it's a fair point. It's too early to say, but certainly worth keeping an eye on.