Our guide to the future of the iPhone continues. Our final topic of discussion is:

Pricing for future iPhones

While we imagine how the iPhone 9 could look, it's also worth speculating about its pricing model, which could be drastically different to the one we're used to. The smartphone market is booming, especially in the Western world, and as competition heats up, we imagine that smartphone providers and manufacturers alike will want to tempt customers with ever-more attractive deals. Could we even see the iPhone 9 being given away for free?

While this may sound ridiculous on the surface, there's method in the madness. Users are accustomed to seeing adverts throughout their mobile device - on websites, in apps, before (and sometimes during) online videos - could it get to a point where smartphone adverts appear on more intrusive places, such as the lock screen, in return for a partial or total discount on the phone itself?

While we're still some way off network providers giving away free smartphones in return for intrusive ads, it's not as unimaginable as some may think. Take Tesco, for example, which has worked with an Australian company called Unlockd which developed the Tesco Mobile Xtras app. The idea of the app is to show pre-approved adverts as soon as you unlock your phone, and while this may seem annoying to some, if you view an ad a day for 21 days, you'll get £3 off your monthly bill. Yes, there's a difference between £3 a month and a free iPhone, but the potential is there. Read next: Best cheap iPhone deals UK

Macworld poll: What do you want from your future iPhone?

It's your turn. Which of these ideas appeals to you, or are you looking for something else entirely? Have you say in our poll.