For a few weeks now we've been hearing rumors about an enhanced version of the OnePlus 3 coming in the near future. At first this was said to bear the OnePlus 3s moniker, but later that became OnePlus 3T. Either way, this is expected to be a slightly upgraded device compared to the currently selling OnePlus 3. However, if a new rumor pans out, it seems like those upgrades you're getting won't be free - as in, the 3T will not cost the same as the 3. OnePlus' current flagship starts at $399, but according to Evan Blass (a.k.a. @evleaks) the new OnePlus 3T will be around $80 more...
Source: http://www.gsmarena.com/upcoming_oneplus_3t_is_rumored_to_start_at_around_479-news-21313.php