Most of our devices are designed to be used one at a time, and not together. Sure, they sync data over the cloud , but they’re still designed to be used one at a time.
Apple took a step forward with Continuity, which lets your Apple devices work together. For example, you can send and receive SMSs from your iPad or Mac. And you can turn on tethering from your Mac, assuming that Bluetooth is on on both devices — the Mac then asks the iPhone to turn on its Wifi interface, and start tethering. You then see your iPhone’s battery and signal status on your Mac.
If you’re using an app on one Apple device, and then switch over to another one, you may get a notification on the second one inviting you to continue that activity. That’s a great idea, but not enough. You’re invited to continue only the last activity you were doing on a device. What if you switched to another app? You then can’t continue the original activity you were doing, on another device. To fix this, maybe the OS should let you choose between the last half a dozen activities to continue.
Apps can also have functionality that let you easily continue what you were doing in another instance of the app, like how Chrome shows you tabs in other instances. Or how Google Maps let you send directions from the PC to mobile. This should be standard functionality for all apps that stand to benefit from it.
Notice that we’re talking about both pull and push — you can pull activities from another device to continue on this one, or you can push an activity you’re doing to another device. For example, while it’s good that Chrome lets you see what tabs you have open in other instances, I usually find myself needing the opposite: if I’m reading an article on my phone, and realise that it’s better read on the PC, I’d like to be able to send it to my PC from my phone. Or, if I’m reading something on my laptop on the weekend, and it’s work-related, I may want to send it to my desktop at office.
So, transferring tasks require both the pull and push paradigms, and they need to be built in to all the apps that would benefit from it.
Transferring tasks is only one way multiple devices can work together. What if you want to use your iPad as a second screen for your Macbook? Maybe you don’t have an external monitor, and a 10-inch iPad is big enough to display a second screenful of content, like your Inbox, a text editor where you’re taking quick notes, or anything else. There’s an iPad app called Duet that does exactly this — it makes the iPad act as a second screen, and it uses a wired connection to reduce latency and to have a reliable connection.
In the opposite direction, Apple should make a Trackpad app for the iPad, which converts it into a Magic Trackpad.
You should be able to send an AirPlay stream to any iDevice, or Mac with a built-in monitor. Which means iMacs and Macbooks. For example, if you’re watching a video on your iPhone, and you want to watch it on a bigger screen, you should be able to send it to your iPad or Macbook Pro. Or vice-versa, if you’re leaving home, and want to continue to watch the video. AirPlay is logically no different from Handoff — you’re handing off a video to another device. iMacs would make excellent AirPlay receivers, since they have big screens and no battery power constraints. Apple should also work with monitor manufacturers to have wide support for AirPlay in monitors.
If connecting to a screen works wirelessly, it should work with a wire, as well, for higher quality video, lower latency and higher reliability. All Macs with builtin monitors – iMacs and Macbooks — should be able to accept video input over any and all video output ports they have, like USB type-C, Thunderbolt, DisplayPort and HDMI. In other words, if an iMac or Macbook has a certain port to connect to an external monitor, it should also be able to function in reverse.
Apple has something like this called Target Display Mode, but it works only on iMacs, not on Macbooks. And that too not on the new 5K iMac. And it’s fussy regarding what what protocol it accepts. This is a shame. It should work on all Macs with builtin monitors, and it should work over all ports and cables that work for video output.
As an example of how this would be useful, imagine sitting at your desk, with an iMac and a Macbook. You’re working on your iMac, but you’d like more screen space. You could plug in your Macbook, and use it as an external monitor.
As another example, you should be able to plug in an iDevice to another one, and use the bigger one as a display . Or plug in an iDevice into a Mac, to use the Mac as a screen.
To summarise, all iDevices and Macs with builtin screens should be able to receive video input, via AirPlay, or via a wire. Standalone monitors should also support AirPlay.
Let’s break down some of the barriers between our devices, so that they work well together, as we need them to, rather than pretending that each is an island onto itself, to be used alone.
 Apps running on your devices should also be able to sync with each other when they’re offline. Imagine being in a plane, without Wifi, and charging your phone from your laptop, while you use your laptop. If you have the same app on both devices, and one has more recently updated data than the other, the changes should propagate to the other one over USB, Bluetooth or Wifi — whichever is available at that time. If you compose a mail on one device, the draft should be autosaved on both devices, so that you can continue on the other one. And when you send the mail, it should go to the outbox on both devices, and be sent as soon as one of the devices is connected to the Internet.
 Assuming both use USB type-C, which I hope is just a matter of time.