The all-new Xperia Z1 may be launching just now, but it seems Sony is already getting ready to launch a new version this spring, in April, most likely to have an answer to the Galaxy S5 and HTC One 2 (or whatever HTC will decide to call it). Sony announced the Xperia Z at last CES, so it's also possible they will launch this new Xperia Z2 at CES next year, too, although other rumors say the opposite - that Sony won't be launching a phone at CES this year.
The rumors about the phone's specs are also quite contradictory, as they say that it will have a 5.2" IGZO Triluminos display, but at the same time they say the resolution will be the same 1920x1080 with a 506 PPI. That seems like a high PPI for a 5.2" display with a 1920x1080 resolution. At that size and at that resolution, it only resolves to 423 PPI. I doubt they changed the resolution from the Z1, so the rumors might be wrong either about the screen size or about the PPI (more likely).
If it's indeed moving up from 5" to 5.2", that gives me hope that they will be able to make a phone with tiny bezels next year, too. That makes me glad because they are one of the few top OEM's left with huge bezels on their devices (HTC is guilty of it, too). Everyone seems to have maximized the screen-to-bezel ratio.
Other rumors about the Xperia Z2 say that it will have the same 20 MP camera, but with Xenon flash. Xenon flash works great in low-light because it's both powerful, but also very fast, and helps take pictures with no blur. This is something I'd definitely like to see more OEM's adopt, along with OIS, and larger 1.2.3" (or even bigger) sensors, which I'm sure the new Xperia Z2 will have, too. One problem with the Xperia Z1 is that because of such a large resolution, it takes about 2 seconds to take a picture and process it. That's way too slow these days, and quite frankly unacceptable. If Sony can't fix this, then they should stick 13MP sensors, which is what I believe the sweet spot between details and speed.
The phone should also come with 3GB of RAM, 3,200 mAh battery, and a Snapdragon 800, which is the same processor Xperia Z1 has. To me, that doesn't make a lot of sense, and it will probably give Sony a pretty significant disadvantage, if everyone else is moving to 64-bit processors by then (and they probably will). They should wait a month longer or whatever is necessary until they can get that, too, otherwise the Xperia Z2 might not feel like a true 2014 flagship. That device will at least arrive with Android 4.4, so that's good news.