Those are not really relevant. First one is ex-LHR only. Second doesn't mention IAH and is a flash sale. Third is a question about fares dropping to the $2K range, not a thread about fares actually being in that range. Fourth is Thanksgiving, not summer.

In the mid-to-late-2000s, every summer CO had a sustained, 30-day or more sale period when one could buy $2K BF fares for most of the summer (as long as seats remained available at the price). Haven't seen that kind of sale in several years.