Sony finds itself in a peculiar situation. The Japanese company that has always had a smartphone at the head of its portfolio of mobile devices all of a sudden names a tablet, the new 10-inch Z4 Tablet, as its most advanced device. It has the new cap-less waterproof USB port. The latest Snapdragon 810 processor. The high-resolution display. The impossibly thin design. It runs the newest version of Android and it supports Sony's PS4 Remote Play. It's everything you might expect the Xperia Z4 to be, but it measures 10 inches.

Where is the new flagship smartphone?

It's painfully obvious that Sony intended there to be an Xperia Z4 to launch alongside the Z4 Tablet. The company has moved on to its 4 series of mobile devices with the introduction of the new M4 Aqua smartphone, which also has a USB port that doesn't require a flap and a new 64-bit processor from Qualcomm. Both the M4 Aqua and Z4 Tablet make perfect sense as accompaniments to a leading new smartphone from Sony, but it doesn't seem like we'll be seeing one making its debut here at Mobile World Congress.

I asked Sony about its flagship smartphone plans and the company said that it's not yet updating the Xperia Z3 series because they're "doing really well in the market." Having reviewed both the Xperia Z3 and Z3 Compact favorably, I'm encouraged to hear that, however everything about Sony's strategy in the past and the way it's set out its other devices here at MWC suggests an Xperia Z4 was planned but pushed back for some reason.

My best guess is informed by the Xperia Z4 Tablet's June release date. Sony's habit is to release its latest products in the spring rather than the summer. It's probably fine to announce a tablet some three months ahead of launch, but if the Xperia Z4 smartphone is going to be released around the same time, it makes more sense to reserve its grand unveiling until later.