Odds of Getting In
You probably won't ever make the big leagues (Disney, tech companies like Apple, and pretty much every fast food chain ever). But there are a lot of companies out there that rely on commercials to sell their goods. The average American child sees 20,000 thirty-second commercials per year. With a client or two and some decent filmography skills, you can probably make one of those commercials.
If you're willing to start low as a production assistant, and you're willing to accept low-budget work, you'll be able to find work.