The new MacBook Pro, leaked in the latest version of macOS. Photograph: Apple

At a press event on the morning of 27 October, San Francisco time, Apple is expected to overhaul its MacBook line of personal computers.

Leading the event is expected to be an update to its MacBook Pro range of laptops, which has not seen any changes whatsoever for more than 500 days. The biggest alteration to the computers has been leaked by Apple itself, when a software update for macOS Sierra included a number of images showing the new computers in action.

One such image of the leaked MacBook Pro, which was first reported by tech news site MacRumors, shows a new touch bar along the top of the computer thatreplaces the function keys, escape key and power button.

The touch bar can be altered in software to show context-appropriate buttons, and at the right hand side of the bar is a separate fingerprint sensor, making the MacBook Pro the first TouchID-enabled computer Apple has shipped. The fingerprint sensor does not appear to be part of the touchscreen, however, with a second image showing a subtle differentiation between the two parts of the computer.

While the touch bar has been leaked in most detail, a number of other reports have also dripped out of Apple’s supply chain. The new computers are expected to have a thinner and lighter body than the existing range of MacBook Pros, and may potentially be the second computers from the company to abandon USB-A, the traditional connection standard, in favour of the slimmer, reversible USB-C.

There is also the possibility that the 11-inch MacBook Air, the company’s cheapest laptop, will be dropped from the line-up, with Apple offering the more expensive 12-inch MacBook – confusingly, largely the same size as the Air, but with a bigger screen – for those who need a lightweight computer for travelling. The MacBook was the first computer in Apple’s line-up to drop USB-A ports, and it only has two sockets on its entire body: one for headphones, and a USB-C port for power and accessories.

Steve Jobs unveils a new MacBook Pro in 2008. Photograph: Justin Sullivan/Getty Images

The MacBook itself was last updated in April this year, and so major changes are not expected, but the 13-inch Macbook Air could see a small speed increase – potentially the last the line will ever receive.

The MacBook Pro line hasn’t been updated since May 2015, when it received a minor suite of upgrades including a speed bump, better battery life, and a “Force Touch” trackpad. Apple had been largely unable to offer bigger changes to the line due to delays in the newest generation of processors from chip company Intel, codenamed Broadwell.

Broadwell processors started to hit the market in mid–2015, however, leaving many wondering why it took Apple so long to offer an upgrade. Compared to the competition, the current generation of MacBook Pros are underpowered.

Even more neglected is the company’s top-tier desktop hardware, the Mac Pro. The computer received a complete redesign in December 2013, but has seen no updates since then. Unless the company has managed to keep potential changes under wraps, that state of affairs is likely to continue: no updates to the Mac Pro are expected.

As for the rest of the company’s hardware line, the Mac mini is almost as neglected as the Mac Pro, with no update on the horizon, while the iMac remains well-supported but with no new hardware expected at this specific event.

With the scale of Apple’s supply chain, the company has grown increasingly incapable of keeping surprises under wraps for events like today’s, with the exception of software changes. But one of them has also been leaked, thanks to the need to do deals with external partners: an update to the Apple TV, the company’s set-top box.

The update will bring a “next generation TV guide”, according to Recode’s Peter Kafka, allowing users to find and watch video content from all their apps in one central location. Well, almost all their apps: Kafka reports that Netflix is a holdout, despite the fact that the video streaming service was previously a launch partner of a similar feature, allowing users to use Siri to search for video content.

While the majority of the major software updates to the Mac line will likely be held until summer 2017, and the company’s worldwide developers conference, it will still need to reveal, at the very least, a new set of tools for developers to work with the touch bar on the MacBook Pro.