Antidepressants are not the next opioid crisis for so many reasons. To think this is the case indicates a fundamental misunderstanding of both these drugs (how they work and what they treat) and what caused the opioid crisis in the first place. To really get into the details would take more time than I have right now, but I'll give you a very brief overview.
First, "opioid" refers to a specific type of drug (one that acts on opioid receptors), whereas "antidepressant" is a general term that can be used to describe many different kinds of drugs. For the sake of discussion though, I'm going to assume you're referring to the most common type of antidepressant which is some form of SSRI (selective serotonin reuptake inhibitor) such as Prozac, Lexapro, Paxil, Zoloft, etc.
Second, SSRIs don't affect you the way opioids do. They don't get you high like an opioid. People are not going to steal money from their relatives to get a quick Prozac fix. You're not going to find someone living on the streets because they lost everything from a Zoloft habit. The truth of the matter is that SSRI can take weeks or even up to a month or more of continued usage to have any significant effect. And for some people, a particular type of SSRI may have little to no effect on them. This is why for many, it takes a lot of trial and error to find the right SSRI at the right dose to have any therapeutic effect at all. Even then, some have to use an SSRI in combination with other drugs to get much out of them. Contrast that with opioids, which don't have anywhere the same variability in terms of psychoactive effectiveness (drug tolerance and pain level aside).
Further, while you do have the possibility to build tolerance and create dependence using an SSRI, this generally only happens over a long period of use. This is why accidental overdoses aren't nearly as common with SSRI. Since SSRIs don't get you high like opioids, you're not constantly upping your dosage to chase the magic dragon. And while you can have problems with discontinuation, it's easily mitigated by stepping down your dosage. Which again, because it doesn't give you a typical high, you don't have rebounding like you do with highly addictive drugs such as opioids. Nobody's falling off the wagon and hitting up a dealer for a quick hit of Paxil.
The final point I'll leave with you is that the opioid crisis is made more severe due to prescription opioids being a gateway drug to other, more dangerous opioids. People that might start out on pills, even if prescribed to them by a doctor for legitimate pain, can sometimes graduate to heroin after getting addicted. I very seriously doubt you're going to find someone say, "Yeah, all it took was a couple of hits of Lexapro and before I knew it, I got hooked on crack".
The reality of the situation is that SSRIs and most other antidepressants have an extremely low risk of abuse. The danger of it turning into the next big drug is so absurd and unlikely that it's almost hilarious. The humor leaves pretty quickly when you realize how bringing this up and popularizing the idea risks further stigmatization of the mentally ill that use antidepressants, and potentially scares away people that should use them, but don't. As someone said earlier in this thread, SSRIs can actually save lives. I realize this isn't your intention, OP, but I would implore you to please do a little more research next time.
As someone with many ties to the educational industry:
For every class in the last few years that I have heard of or directly been involved with, easily half of the students have had specific learning requirements due to medication for depression, ADHD, etc.
I'm not a doctor and have no medical training, but seeing that number increase consistently over the last decade or so...something's wrong. Medications are being handed out like candy.
Is it really that medications are being handed out like candy or that more people with mental illness are now getting appropriate treatment?