According to a recently published report, Apple’s anticipated next-gen Apple TV set-top streamer may not be supporting 4K definition content as some had anticipated. Citing sources who claim to be familiar with Apple’s plans, an unnamed source told BuzzFeed News the following:

4K is great, but it's still in its infancy.
For those of you who didn’t know, a previous report claimed that Apple’s latest A7 system-on-chip as found in the iPhone 6 and 6 Plus was capable of putting out 4K video. If Apple sticks with convention the chip will likely end up powering the next-gen Apple TV, leading some to believe the set-top box would also offer 4K support. With 4K video still being a niche product, Apple’s decision to not include it in current technology does make sense to an extent. As seen with services like Netflix, Amazon and Sony, the amount of 4K content available can be considered limited at best. Furthermore, only a handful of expensive televisions are capable of displaying ultra-high definition at the moment.

The other big issue that appears to be a problem for both consumers and content providers are costs. As of right now, 4K has yet to benefit from any serious industry competition and with low uptake relative to vanilla high-definition hardware, the technology doesn’t enjoy attractive prices which can be afforded by the masses. That being said on Apple’s side, bandwidth support for 4K streaming would also put a large strain on its existing content delivery network. The Cupertino California company began to migrate downloads to in-house infrastructure last July in preparation of iOS 8 but it remains unclear if the network would be able to serve up 4K content. Consumer-grade broadband also appears to be a problem as many US household connections simply can’t handle speeds that require 4K streaming. The report mentioned the following regarding the matter:

Today's report did not say when the next Apple TV is expected to drop, but BuzzFeed previously pegged a debut at WWDC in June. Apple recently slashed current model pricing to $69, signaling a successor is in the offing.
We’ll have to wait and see if speculation proves to be right by being patient.

Source: BuzzFeed News via AppleInsider