The first $100 billion company in travel is coming.

As recently as four years ago, Expedia spun off TripAdvisor and a lot of people thought that was a great idea for both companies. Looking back, it was the most recent step hindering the $1.3+ trillion online travel industry from getting a company to a $100 billion valuation.

Sure, private market valuations may seem frothy and the result of a PR battle and founder ego stroke more than anything, but what’s in a valuation?

Hiring the best talent, building the best leadership teams, getting the best partnership deals and terms, the list goes on and on for what being a titan in an industry provides. Just look at Facebook, a company Yahoo could have possibly “overpaid” a little over $1 billion dollars for not that long ago that is now pushing on $300 billion in market cap. Look at Apple? A company that doesn’t care if Adele is streaming her album or not (like Spotify) because they’re going to rake in plenty from their cut of the 1+ million digital albums she’s set to sell this week.

Looking back, it’s pretty clear that this decade would be the one in which we’d start to see a travel company on track to reach a $100 billion valuation. Travel is one of the few industries that Millennials spend more of their money on than previous generations, unlike mortgages, car ownership and the like. And with an improved economy and globalisation, business travel increases, too.

Uber getting to a $100 billion valuation by 2020 is now a very reasonable thought not only because they’re executing globally, but also because the transportation industry has produced Ford and GM and others.

But Airbnb sitting at a $25 billion valuation which is north of companies like Hilton Hotels is just ridiculous, right? Many public market investors don’t believe that valuation would hold up should they go public today, and they can’t be wrong, right? Well, that’s if you’re only looking at the industry as it looks today vs. what it will look like in the future. That’s if you make the same mistake as investors who passed on Airbnb in 2008 and early 2009.

The true thing you have to consider if you’re trying to see if Airbnb can become a $100 billion company is what Airbnb isn’t doing.

Airbnb isn’t trying to be all things to all people. I have a particularly unique understanding of this strategy because it’s the same thing we’re doing at my startup Localeur, where locals recommend local places to eat, drink and more. It’s why we’ve been able to scale from 1 to 20 cities in two years and grow our user base 1,500% this year alone with only four employees, why our leading investors see similarities between college-era Facebook and Localeur, and why people are starting to see us as the Yelp killer.

In trying to be all things to all people, you advance your product and marketing efforts so broadly that it’s not possible to go deep. And in the 2010s, and with Millennials, community management and authenticity and design are things that involve going deep instead of wide.

You have to win people at their heart before you can retain people with their mental dollars. Small Business Saturday is coming up, and it’s the perfect time for people to understand the unique value of Localeur and what we’re all about: supporting small, local business owners. Black Friday is trying to win someone’s mind. Small Business Saturday is trying to win their heart.

It’s hard to do that, impossible even, if you don’t take time to make an emotional connection and empower your users. That’s what Airbnb is doing right, and what Localeur is doing right now. It’s also the attribute companies like Yelp and Foursquare lost when the focus went from Yelp Elite to earnings (after Yelp’s IPO) and from checkins and mayor status to monetization (after Foursquare’s inability to get past the valuation they reached as far back as 2011).

At Localeur, when we see companies like Google turn their focus to local guides and recommendations, it doesn’t make what we’re doing at Localeur any harder. It makes us flattered that companies with far more resources are swarming toward the very thing we’ve been doing since day one and spending millions to educate the market on how important local is. And once they enter this space, they have to beat us with authenticity and Millennials, which is something no amount of engineers will get you.

Expedia, Priceline and TripAdvisor, like Google and Yelp, are now doing the opposite. They grew up in the early days of online transactions and marketplaces, and have done everything they could to maximize revenue and returns in recent years, which meant marketing to everyone. It was an opt-out model, meaning a lot of people have used their products but opted out over time. It means, they’re not trying to make you aware of what they are or how it all works, but they’re constantly trying to win you back.

With Airbnb, it’s an opt-in model. If you haven’t used Airbnb before, it’s because you haven’t opted-in yet, which likely means they haven’t tried extremely hard to reach you yet…maybe you’re not a frequent traveler or not a Millennial or not living in a major city. They have a Total Addressable Market that they’ve only scratched the surface of through 2015.

In 2020, things will be different, and tens if not hundreds of millions more travelers will have opted-in to the future and opted-out of the past, making it more difficult for online travel agencies to compete and win back customers. I’m OK that Airbnb’s TAM is greater than Localeur’s today. Expedia’s TAM was bigger than TripAdvisor’s, at one point too, and now Expedia has a $16 billion market cap compared to $12 billion for TripAdvisor. The ecosystem is big enough for us both; one focused on lodging decisions, the other focused on user-generated content to inform travelers.

So the real thing to measure in determining if Airbnb will reach $100 billion valuation (on the public market, one can assume) isn’t how many room nights Airbnb is getting or if the major hotel chains add Airbnb as a distribution channel.

The real thing to measure is how many more people are still out there to opt-in to Airbnb (or Localeur) vs. how much harder OTAs (or Yelp) will have to work to win back those same customers.

I’m betting on Millennials and business travelers who control spending for the next 5–10 years to determine the answer, and by 2020, I have a feeling Airbnb will be headed to a $100 billion valuation. It’s a big bet on another company I don’t see the ins and outs of, but it’s really a big bet on Localeur, and I know all about that.

Case in point, last week, I spoke about the importance of authenticity, community management and innovation at the national conference for the American Society of Association Executives, a diverse group including the heads of the American Beverage Association, National Retail Federation, the Society of Petroleum Engineers and the Atlanta Convention and Visitors Bureau, and just 5 minutes ago got a text from a Millennial friend in the medical field saying, “we have 300 people from all over coming to town for a conference and Localeur is now included in our agenda.”

These good folks are new to Localeur, but how many of them know Airbnb?