Though the PS4 has yet to be announced the Internet is rife with rumours and speculation about its specification and features. Whilst most of the information you are likely to find can be completely unfounded there is at least one way of making an educated guess as to what to expect from the PS4 and that is to look at the PS Vita.
Possibly the biggest focus on the gaming side will be the push forward in downloaded games. With the Vita you get a physical game released and you get a digital copy of that game being released alongside it. This is true with certain games on the PS3, although they are often priced far higher than their physical counterparts are. With the PS4 however. we are likely to see the system that Sony use with the Vita to be implemented.
Another feature we are likely to see is a bigger focus on non-gaming functions. This is something we are already beginning to see with the PS3, but it is lagging behind both the 360 and the PS Vita and this is likely to change with the PS4. This may also lead to impacts on the gaming side of the PS4. The PSN is great, and it's also free, but only a raving lunatic would try and argue that Xbox Live isn't vastly superior in terms of its service and that is largely due to the fact that cross game party chat exists on the Xbox and doesn't on the PS3. The PS Vita is also missing this feature but does at least include Skype which is a definite hint towards the PS4 featuring a better chat system.
Ultimately we will have to wait and see and the wait could be a lengthy one with Sony stating outright that the PS4 won't be at this year's E3. Personally I hope to have to wait a while for both the next PlayStation and Xbox because, let's face it, this generation is pretty awesome. But hopefully when we do see the PS4 I can sit back smugly knowing that I was right.