By the numbers, CES is an impressive circus of gadgetry. The annual Consumer Electronics Show in Las Vegas was spread out over nearly 3 million square feet last week, with 4,500 exhibitors showing their wares — the latest in 8K screens, giant drones, walking cars, robot pets and automobile prototypes that would make Bruce Wayne jealous (but will never see the light of day).

Despite the sheer number of things on display at CES this year, the hottest items — most relevant to marketers and game-changing for average consumers — can't even be seen. From the artificial intelligence increasingly powering, well, everything, to the forthcoming fifth generation of telecommunication technology, the most exciting stuff at CES couldn't be touched.

Here are four key takeaways Ad Age correspondents picked up from the floor — and from conversations with gimlet-eyed experts.

The industry is pushing "connected everything"

In the third season of "The Simpsons," Homer Simpson's entrepreneurial brother, Herb, struggles to come up with an innovative product that will make him rich. Homer offers him some advice: take "an existing product and put a clock on it."

That same logic was applied in full force this year at CES, but instead of a clock, companies are adding connectivity to products — be it diapers, toilets, lawn mowers and even physical bottles, such as Procter & Gamble's "Facial Treatment Essence Smart Bottle," which rewards its users each time they apply the product's serum.

Fueling the connected everything movement is the next generation of mobile technology, 5G. Once fully deployed (which is unlikely to occur within the next two years), consumers will see speeds that allow them to download a two-hour movie in two seconds.

Beyond that, 5G's true objective is providing the fuel for a connected everything world. Some 50 billion connected devices will exist come 2020, and those devices will generate 4.4 zettabytes of data, up from just .1 zettabytes in 2013, according to Cisco (there are 1 trillion gigabytes in 1 zettabyte).

Yet with so many companies struggling to make sense of the data they already have, a connected everything world will only exacerbate that problem. Meanwhile, those same companies are struggling to protect consumer data at a time when an increasing number of people are becoming wary about how their data is used.

All of these connected devices will come from different companies and likely exist in different ecosystems; will a smart Samsung fridge be able to speak with a smart LG stove? Probably not. Will smart cities improve infrastructure and make them safer, or will they become more vulnerable to hackers and system failures?

Perhaps at next year's CES, companies will look to answer these critical questions instead of hyping the promise of a connected world.

The war for voice dominance will be fought in your pocket

Although we are now just a couple of years into the development of voice and smart speaker technology, a duopoly has already emerged.

An entire cottage industry of third-party products has blossomed around the two — smart light switches and smart microwaves that boast "works with Alexa" or Google. It has created, says Jared Belsky, CEO of 360i, a "flywheel" effect that serves only to strengthen the duopoly's dominance.

However, if Belsky were to place a bet, he'd say Google has the advantage. "The war on voice is going to be won in your pocket, on your mobile device. Not your smart speaker," he says. "What's less understood is that Google is coming on extraordinarily strong, and its advantage is the smartphone. It's Android; it's what's in your pocket. That's going to lead to a lot of strength for Google."

AI is already ubiquitous

This year more than ever, conference attendees are able to chart the progress of artificial intelligence in the marketplace.

"The big changes this year versus last year is the humanization of AI and how completely ubiquitous it has become into our lives," says Allan Cook, the digital reality business leader at Deloitte Digital. "If you look at voice-enabled devices, you see that you use it all the time. Last year it was a new toy. My family, we got them for the first time. Now everyone is ordering everything from their favorite device."

Adds Deirdre McGlashan, global chief digital officer at MediaCom: "We keep thinking it's this thing that's just around the corner. But it's already infiltrated our lives," she says of AI. "It's in a lot of the parts of the infrastructure that we use that we don't even know about," from recommendation engines at online retailers to air traffic that guides our planes.

And yet, despite its ubiquity, uncertainty hovers around AI. "Everyone is worried about the robot army coming and creating a doomsday scenario," says McGlashan. "But I think the real risks are [in not] understanding, when you're using products with AI in it, what was the data that was being fed?"

Smart kitchens are still not a thing

Smart kitchens are a hard sell and they have been for a long time; it's unclear what problem they're actually trying to solve.

LG touted its "future of smart kitchens" at this year's CES. Features include automatically preheating the oven when selecting recipes from Drop, a popular app that provides recipes.

The company says its collection of connected appliances – refrigerators, dishwashers and ovens – will "work together to help simplify the task of food preparation as well as meal cleanup." Yet it's not difficult to preheat an oven, or push buttons on a dishwasher. And while most people expect their appliances to last at least a decade, how will the added technology hold up in the long run?

Other companies, such as Samsung, are adding apps to its smart appliances, allowing consumers to do things like search for recipes. Of course, recipe selection is something people can already do, perhaps more efficiently, with their phone, laptop or tablet. Samsung did add it will text owners of its smart fridge should they accidentally leave the door open, a mildly neat feature, though not especially helpful if you're not at home.

All these smart features will come at an additional cost to the customer. The customer will decide if they want it.