Despite numerous reports floating around in regards to upcoming Xperia devices, Sony continues to keep a tight rein on its future mobile plans, which is why the latest unofficial pic starring the Z1 next to a mystery handheld leaves us all scratching our heads.

Sony Xperia Z1 Mystery Sony handheld surfaces online, could be rehashed Xperia Z1 or upgraded Z2

What is the ever so slightly larger phone clinging to the purple Z1? It can’t be the international version of the Z1 f (aka Z1 mini) for obvious reasons, so it’s likely a Z1 follow-up of sorts.

Here’s a wild theory. What if the oft-rumored Z1s isn’t the global Z1 f either and the “s” actually stands for “supersize”? Hard to buy, but that’s why it’s called wild. And the most questionable part isn’t the somewhat confusing moniker.

Instead, Sony’s angle for a 5.2 or 5.5-inch Z1s would be very tough to crack. They aren’t ready to roll out a full-on sequel for the spectacular Z1, so they decide to do a half-ass job and, say, upgrade the software, maybe the Snapdragon 800 CPU to 805 and nothing else? Then how are they planning to battle the likes of Samsung’s Galaxy S5?

Sony Xperia Mystery Sony handheld surfaces online, could be rehashed Xperia Z1 or upgraded Z2

Not an easy question to answer, thus I’d rather follow up on a couple of other leads. For instance, the gizmo pictured above could ultimately be the Z2, aka the rightful successor to Z1’s throne. No one says Sony has to up the size ante too much or completely overhaul the design, with CPU, RAM, battery and resolution improvements possibly doing the trick in keeping the OEM in the high-end race.

Lastly, another theory is we’re looking at a Z1 specifically designed for T-Mobile, the sole US carrier rumored to score the device. There’s even a chance the Magenta-bound Z1 is actually the one dubbed Z1s, though it’s unclear if the “UnCarrier” would be allowed to operate any other tweaks aside from a size increment.

What say you, dear readers, which of the three interpretations do you regard as the most plausible?

Sources: Xperia Blog, Tech Radar, Digi-Wo