Hello everyone. First post. :-) I'm a journalist and we had a Sony "launch party" yesterday night (with accompanying presentation for the new models) which brought some very good OFFICIAL news.
One of the top people of the X9 team at Sony Japan was present and took part in the presentation, where he clearly stated that Sony Europe will DEFINITELY give X9 owners a clear upgrade path in the future, in hardware as well as software terms. That includes the HDMI 2.0 spec, as well as the H265 codec. He refrained from sharing details, as he said that IFA 2013 is just around the corner (September) and they'd prefer to make announcements there. He promised, though, that "people who buy these new TV sets will get to enjoy them fully for many years to come".
Unofficially, what many of us journos suspect is that Sony knew the approximate commercial timeframe for these 4K TVs, foresaw that the "next step" (HDMI 2.0/H265) would not have been completed by then, so they designed the sets to be at least partially hardware upgradeable (even if it's just the HDMI ports and associated boards). It's not "modular" per se, as is Samsung's Evolution Kits for instance, but it seems to be enough. In any case, our primary concern is 2160p/60 and H265... and these seem to be covered.
What I personally think is that the relevant process will take the form of the replacement that you lucky people with the 4K player are doing at the moment. A company technician will probably come to the customer's residence and replace the HDMI boards/ports with the newer version, perform a firmware update (probably one that won't be available online) and... voila.
The Japanese engineer would not commit to a cost for that, of course, and I cannot vouch for all this without a shred of any doubt until I get my X9 (late August since I'll be leaving on vacation soon) and open it to see how the electronics at the back are configured. But I really do not think that Sony would officially commit to something they are not certain they'll be able to do. So there. :-)