Maxis released a teaser ad that stated the OnePlus 2 would be coming in by 22 September. This was discovered after Lowyat.net discovered it via a cursory Google search.
Clicking on the ad would just direct users to the Maxis website and a registration of interest. Maxis subscribers will likely get notes or emails as the date nears though it'll be interesting to see if Maxis will hold more promotions to clear stock of the OnePlus One it currently has.
So if you've been considering getting a OnePlus One from Maxis, it might be worth your while to see if the OnePlus 2 would be a better deal. For sure, it will cost a bit more than its predecessor so if you're counting the pennies, the OnePlus One is still a very good phone for its price.