Replacement Panel ? For me, my whole Z1 compact was replaced because of a single dead pixel(the service person told me that they don't open any of the Z series cells, just replace them outright). As for Z4, this particular model will be released as Z3+ outside Japan. Heck, even Sony is not considering it as a flagship. I guess we have to wait till August for the true Z4 to appear ? This approach is rather strange and is like Apple iPhones, whereby the overall dimensions and looks of the device remains same, but internals are updated during mid-cycle. The only thing Sony is lacking....is software to drive the hardware. Sadly, it is an irony that Sony sensors are powering nearly all the flagships of 2015, but Sony can't make them work on it's own cells. I miss the old Sony Ericsson days......
Xperia Z4 to be marketed as Xperia Z3+ globally? | Xperia Blog
iPhone is different, I was referring to update cycle pattern. The product segmentation from Apple differs vastly from Sony. Z1 shared the flagship crown with Z Ultra and Z1 Compact, whereby they were flagship compact and flagship phablet respectively. In case of Apple, 5s was a single piece(5c....completely forgettable), and hence by default a true flagship. Z4 as such cannot be considered one, given the low profile release and no global announcement. I think they want to keep the 6 months release cycle, with complications of having devices in market selling at similar price(Z2 and Z3...not much difference in specs and price). Either Sony is trying to close all the loops and planning to end its mobile operations, or they are creating something in lines of Galaxy S6, a rather radical Z5.
Honestly, I don't think Sony can pull another Motorola, given that Kazuo Hirai is more interested in sensor and playstation business, rather than focusing on core Bravia and cellular business. I can see another Sharp in making, a company more focused on providing OEM components and niche consumer electronics. Can't blame the management too as it is imperative for them to show profits, but neglecting divisions is a bad way to end them.