The description of the teaser reads “This is a teaser for something we’ve been cooking up”, further suggesting that this could be an update. However, the accompanying image says “What are the two things you can’t live without?” with a OnePlus One on either side.
Keeping this in mind, it’s possible that the company is talking about something else entirely here, so we’re not getting our hopes up just yet.
Also since the Android 6.0 update for the OnePlus One has to come from Cyanogen strongly suggests that this is a project that OnePlus has been cooking up on its own. Perhaps the company is talking about the Android 6.0 based Oxygen OS? We can’t rule out the release of new hardware at this point either.
The OnePlus 2 and the OnePlus X are still running on Android 5.1 Lollipop, so it would be a little strange if the company’s two year old flagship gets an update before the newer devices. We’ll stay tuned for more information on this particular teaser.