Preview at WWDC likely in June, followed by September launch.
New 15-inch MacBook Pro and 27-inch iMac Expected to Launch This Wednesday
The website cites an unnamed source who has provided accurate information on a number of occasions in the past, but provides no further details regarding the exact specs and upgrades that could go into the two new computers. Given that the 13-inch MacBook Pro was updated back in March with the expected processing and graphics boosts, as well as a new Force Touch trackpad, it's safe to say the new 15-inch model should receive similar upgrades.
As MacG.co points out and we have discussed in recent days, shipping times for the 15-inch MacBook Pro have been slipping, sparking speculation of a WWDC reveal for updated models.
It is unclear exactly what processors will be included in the new MacBook Pro, as Intel's timeline for Broadwell chips had previously estimated a July-August release for chips appropriate for the machine. Intel did, however, quietly launch a few higher-end chips in the Broadwell family two weeks ago, suggesting production may in fact be ahead of schedule.
The site doesn't touch much on the iMac update, beyond pointing out that the only model with a delayed shipping estimate is the higher-end non-retina 27-inch iMac with a 3.4 GHz processor. We noted slipping shipping estimates on iMacs a month ago, but while most of the models returned to "in stock" status shortly after, it now appears Apple has indeed been drawing down stock ahead of this week's update.
Delayed shipping times in the weeks ahead of a major event like WWDC generally appear as good indicators of what product categories may be getting an update, but given recent updates to the MacBook Air and 13-inch MacBook Pro, the release of the new MacBook, and the pending 15-inch MacBook Pro and 27-inch iMac updates, Apple could once again have a software-focused WWDC keynote similar to last year unless it decides to show off an update to the Mac Pro.