Apple (AAPL 1.27%) has teased its fans with each successive iPhone release. 

The company offers new features or improves specifications in ways that often delight its user base, but there's always something missing. The last iPhone release offered a bigger screen -- something people had been clamoring for -- but it failed to deliver on a number of features iPhone users have long been waiting for.

Here are a few features three Fools hope the company adds when it releases its next phone.

Tim Beyers, better sharing features: Have you ever noticed how difficult it can be to share anything using an iPhone? Messages is a good example: Apple's self-contained messaging system is great for communicating between two Apple devices, and terrible for just about anything else.

Facebook (META -0.52%) recently admitted the folly of trying to force users into its ecosystem when it unhinged its own Messages app from the parent platform. Now anyone with a phone number can download and use the software -- no Facebook sign-in required. Don't be surprised if adoption in emerging markets soars as a result, leading some who've never heard of Facebook to try out the social network.

Now imagine if Apple tried something similar. Imagine if an Android user like me could authorize my Mac-based messaging accounts in the Hangouts messaging app on my device. For one thing, I'd use the Messages app on my Mac almost exclusively.

Conversely, what if Messages on the iPhone could seamlessly handle a wide variety of services -- from Google (GOOGL 0.55%) (GOOG 0.74%) Hangouts to WhatsApp to Messenger and more? What if it was the go-to for helping iOS users find and connect with people on any platform? Removing connectivity issues would allow consumers to focus on the hardware, which, according to CEO Tim Cook, favors Apple.

Cook says 99% of people who have an iPhone "love" it. Opening up Messages and increasing other avenues of integration won't make consumers love their handsets any less, and it may help win back Mac-using, Google-addicted Android converts like me when the 6s makes its debut.

Daniel B. Kline, an improved Siri: When Siri was introduced with the iPhone 4S, it seemed like it would revolutionize how people interact with their phones. The problem is, the voice assistant has never worked well enough to be all that useful.

Siri does not always return the information you were hoping for.

Siri is a good idea in theory, but in reality, it's a novelty -- like handwriting recognition on the old Apple Newton. It's simply wrong or not available too often to be counted on.

Apple has made slight improvements to the voice assistant since it launched, but it needs to overhaul it completely. Microsoft's (MSFT 0.37%) Cortana has shown that a high-quality, accurate, and useful voice assistant is possible, and Apple should either improve Siri so it works as well as its rival, or do the unthinkable and make a deal with Microsoft.

A voice-controlled iPhone offers endless possibilities, but it has to understand what you're saying and correctly interpret the information you want a very large percentage of the time. If Apple could deliver a Siri that does that, it would have an iPhone that truly represents a leap forward.

Steve Symington, OLED displays: As a longtime shareholder of organic light emitting diode technologist Universal Display Corporation (OLED 1.65%), I'm counting the days until Apple finally incorporates OLED displays into its iPhone line. And yes, tech industry watchers have followed rumors of Apple's impending shift to OLED for years, even after CEO Tim Cook offered sharp criticism in early 2013 of OLED's brightness, color saturation, and color accuracy -- a not-so-subtle dig at Samsung's longtime use of OLED as a key differentiator in its flagship Galaxy line of smartphones and tablets.

As it happens, Apple is now using flexible OLED displays (manufactured by Universal Display customer LG Display) in all versions of its new Apple Watch line, and DisplayMate has praised it as a "very good side-by-side match to the iPhone 6." Going even further, DisplayMate also insisted "OLED display technology is now challenging and even exceeding the performance of the best LCDs" after a series of continuous improvements in recent years. And that's not to mention that OLED can be made impossibly thin, flexible, and even semi-transparent. 

Perhaps it should have come as no surprise, then, when LG Display announced plans a few days ago to invest roughly $900 million in building a new OLED plant in Gumi, South Korea, with the aim of mass production by 2017. This confirms previous reports from BusinessKorea speculating as much last month, when a source familiar with the situation stated, "It is very likely that the first flexible iPhone may be introduced in 2018."

In the end -- and this isn't just the Universal Display shareholder in me speaking -- I'm convinced it's only a matter of time until Apple expands its use of OLED to its flagship smartphones.