A whole bunch of leaked documents posted by SonyAlphaRumors make it clear Sony is ready for 8K:
1) Sony has finalized the new XEVC 8K code (details on SAR).
2) There is a 60MP 8K sensor (details on SAR).
3) There is a 36MP 8K sensor (details on SAR).
No don’t get too excited: While sensor and codec will support 8K the hardware might not. Processor speed and heating issues might be the limiting factor here. I expect 8K to be implemented on large camcorder bodies first, It might take 1-2 years before we get in on more normal sized compact mirrorless cameras.