Have we seen the best that the smartphone has to offer? Has the smartphone, as a technological device essentially hit its zenith? Is it all downhill from here?

It's not an overstatement to say that smartphones have revolutionized countless businesses and industries. The handheld devices have become the linchpin for everything from automotive to healthcare to social media markets. The gadgets have subsumed countless other devices, including cameras, camcorders, watches, music players, pagers, traditional telephones, and even -- for many, many tasks -- desktop computers. They're used as radios, video conferencing systems, portable video game machines, and televisions.

It's why 334.4 million smartphones were shipped worldwide during the first quarter of this year and another 377.6 million were shipped the previous quarter, according to tech research specialist IDC. There is also plenty of opportunity in developing nations with little infrastructure for economic and public health benefits thanks to increased use of these handheld computers. However, one might wonder whether smartphones have reached their pinnacle in terms of what they can actually accomplish individually.

During a recent spate of testing new products, software, and services, I began to think the smartphone has had its day. Yes, it's extremely useful for many tasks -- it can measure my blood flow rate and recognize my voice -- but it's extremely ill-suited for many tasks.

The Internet of Things, for example, is thought to be inextricably tied to the use of smartphones. It can give you a view of your infant's room at night, allow you to adjust the temperature at home while you're at the office, even let you open the blinds or turn on the lights from anywhere in the world.

But it can also become a digital albatross, complicating your life rather than making it easier. Consider the smart front door lock. A smartphone can automatically unlock it as you approach with an armload of groceries, or let the kids in when they've forgotten their keys, or allow a delivery person to leave a package safely inside. But late one night when I arrived home, the batteries in my front door lock had died so neither the smartphone nor the lock's numeric combination worked. Of course, I'd been lulled into smart home laziness and had not bothered to keep my backup physical keys with me. Damn.

Over reliance on smartphones isn't the only problem. The technology may be starting to overreach its abilities. Consider a Bluetooth kitchen thermometer I've been testing. The gadget is designed to flash a light to tell you whether the probe you've poked into the Sunday roast has registered the right temperature or not. It will beam the precisely measured temperature to your smartphone. So in addition to monitoring your sous vide timing and chopping vegetables for the salad, you've got to pay attention to two more gadgets. And, of course, the Bluetooth thermometer requires a battery. So why abandon the old fashioned mechanical thermometer, which is faster, just as precise, and doesn't require replacement batteries?

(For the smarty-pants who counters that we can get recipes on a smartphone, you can do the same on a more legible tablet)

Another area where smartphones are making inroads is in cars. Connected dashboard systems are increasingly reliant on connected phones for streaming music services, messaging, and maps. Apple's CarPlay and Google's Android Auto are pushing such connectivity while hoping to alleviate the problem of driver distraction. But these systems have inherent limitations: neither, for example, can turn up the heat or check your tire pressure. And they won't gain these abilities anytime soon, if ever. So much for how intrinsic the phone will be to the future automobile experience.

Consider as well that smartphones could replace the keys and wireless keyfobs used in most cars. A phone can easily be used for proximity systems that unlock your car as you approach. There are already apps for remotely starting your car, opening the windows, or checking the charging status of an electric vehicle. But a wireless key fob's battery will last for more than a year, while a smartphone could die on you at any moment, leaving you stranded. (Not to mention that phones require a GPS signal and cell connection for most tasks, factors that you cannot always count on)

The lesson isn't that smartphones stink. And it's not simply a matter of newer, smaller gadgets coming along to usurp the phone. Smartwatches (given time) may replace phones, but they'll suffer from the same limitations. I’m not even disappointed in the progress of the Tricorder Project or the Tricorder Xprize competition to turn smartphones into the omnipotent gadgets from Star Trek.

No, the moral is that all the features we love in smartphones are about to be absorbed into many of the devices that now seemingly rely on smartphones.

Getting into your car and then connecting a phone to the dash -- and hoping you have a cellular connection just to play your favorite tunes seems like a backward step. Heck, 8-track tapes are easier to use. This fact has not been lost on automakers who are adding more built-in cellular connections and touch-screen based systems with voice recognition to their cars now.

Eventually, someone is going to wonder why we're bothering to funnel Pandora or live maps through our smartphones when we could do it more quickly and more conveniently directly in the dash. No more cables or connection hassles. No worries about remembering your darn phone.

It may be that relying on a single device is always a bad idea. We need redundancy and standalone features. A smart refrigerator should have the brains built-in and not have to rely on an iPhone. And you should be able to open the front door even if you forget your Galaxy S6.

The smartphone may not have quite had its day. Indeed, it may have many, many more days to come, but technologically speaking, it's clearly time for us to be looking for our next digital champion.

John R. Quain is a personal tech columnist for FoxNews.com. Follow him on Twitter @jqontech or find more tech coverage at J-Q.com.