When Microsoft and Sony are ready with 65u parts, I highly doubt you'll see any news or official statements indicating when those are shipping. Rather, each vendor will simply begin populating new consoles with the new parts. You won't see any markings on the boxes indicating anything is different. Aside from hardcore enthusiasts looking at build dates, 99% of consumers won't know whether the console they're looking at on a store shelf has either 90u or 65u hardware inside.
A perfect example of this is actually Sony's PS2. Go google how many motherboard revisions the PS2 experienced (all unannounced) before it was made into the new slimmer form factor and you'll see that a console vendor can make as many internal changes they want. The only time they'll alert consumers to these changes is if the functionality of the unit is changed. So long as the console does everything its supposed to correctly, they can change every component inside the box and not have to say a thing.
The key to "spotting" newer systems featuring the 65u parts will be very similar to seeking certain steppings or OC-friendly batches of CPU's. The serial number (or some other marking) will likely give a clue towards build date. Once enthusiasts get a feel for what codes are using the 65u parts, you'll find out what numbers to be looking for...