The tipsters don't have full details, but it's expected that the screen would use Thunderbolt 3 (which relies on a USB-C connector) to connect both the display and GPU. You probably wouldn't need the multiple video cables of existing standalone 5K screens, then. Also, it'll supposedly be "very similar" to the current-generation 5K iMac's display, complete with movie-grade color accuracy.

There's no mention of a firm release schedule. However, people have noticed that Thunderbolt Display stock is running low at Apple Stores around the world. It wouldn't be a stretch to imagine Apple unveiling a 5K monitor (and maybe a Mac built for it) at WWDC in mid-June, when many pro Mac users will be watching. If and when it shows up, it'll arguably be overdue. Mac Pro users have been crying out for a higher-resolution Apple external display for years -- after this, they wouldn't have to consider switching to an iMac to make that happen.