Personally I expect things to become very boring. Why? - Because there hasn't been any real innovation in the mobile market for the last - almost - ten years. Let me try to explain:
The first iPhone - though highly influential - was not an innovative device. It had three design-decisions that made it stand out, and affected every other design decision: 1. looks over battery-time, 2. multi-touch (which Apple at the time claimed it patented, but was neither invented by them, nor exclusively bought), and 3. the internet was essential. If you compare the OS of the first iPhone to a Palm PDA like the TX you have a mostly similar design; being centered around a grid of apps. Unlike all smartphones at the time (the iPhone 1 was not a smartphone but a featurephone) it did not have any apps (which the exception of some webapps where you need to be connected to the server all the time). It also had specifically a focus NOT on being a phone (and had worse reception than any other phone at the time). The first iPhone as a multimedia device that doubled as a phone with bad battery life, limited features, but a bright and shiney look. Other smartphones at the time were exactly the other way around. But let's be honest: looks sell, and few people at the time knew the power (and usefulness) of real smartphones.
Being so influential, however, caused all other phone-makers to adopt Apple's design-decisions. And while Steve Jobs said at the iPhone's introduction that they were five years ahead of the competition, in reality the only thing that really distinguished them was the decision that battery-time was unimportant. And with that notion every other company could create their version of this concept.
Most innovations that we've seen in the phone-market came not from the large companies (Apple, Google), but from small third-parties that were bought. Other than that, most features are focused on adding features not usefulness, and the common OS's have become bloatware for years.
And that brings me to the question: can the Duopoly be broken? - Maybe. But in my opinion the way to do it is to not make a phone at all. Now let me first say that a few months ago I got my first mobile phone through work, and I really don't know what the fuzz is about. I have used PDA's in the past, and I understand the fun of apps, but the idea of always-on-call, always-online or even the internet-of-things simply doesn't appeal to me. That being said, I really believe that the only way to get into the phone market is by not building a phone at all. Apple did this correctly with their first iPhone: they build a multi-media device that could also make phone calls (and then they stupidly called it a phone).To break the mold one has to create a device that is focused on a specific task, and work from there. The risk of this is, that people will ask the question: why should I carry another device if I already have one that can do this and more?
So the focus-area - in my opinion - should be communication. So we're not making a phone, but a communication-device. Making phone calls just happens to be one of the ways you can communicatie. The device should not be sold (primarily) through phone companies, a SIM card should not be required (especially with more and more open WIFI networks in cities), but should be an option to the user. This same approach should also break away from apps as much as possible, since the goal of the user is not to send someone a message through WhatsApp, but to send someone a message, to communicate. And this approach should be at the heart of everything. The interesting thing is, that such an approach is in line with the design-rules of mobile devices: focus on a single and simple task. It's odd that existing operating systems do exactly the opposite (in hopes to cater to the masses). All that being said, I don't think this device will have a mass-appeal, because I doubt people will understand it (or be able to classify it as anything). So yeah...it will be a financial failure. Also, companies like WhatsApp will never allow their something like this, because it breaks their proprietary ecosystem.
So yeah, it's going to be very boring in the phone and tablet market. We have two giants that don't really innovate, and we have a lot of users who a. bought into an ecosystem, and b. aren't really interested in anything truly innovative or different, and (essential) app-companies don't want to risk anything.
ps. why was Microsoft missing from your list. Because you can say whatever you want about Microsoft, but at least they thought about their OS, and wanted to make something different (that - as far as I've seen - mostly works).
pps. end of my personal rant.