Vendors can help reduce the congestion problem by developing APs that are more flexible and avoid the psychological sunk cost problem all-together. The future is software defined... Software Defined Radios (SDR).
APs with more flexible options and band unlocked radios are on the horizon. This is sometimes also called software-defined radios (SDR) (although there are distinctions that are beyond the scope of this post). Vendors can help alleviate 2.4 GHz spectrum congestion by eliminating the perceived loss that comes with unused radios. They have made minor sales and marketing attempts at this already, telling customers that unused 2.4 GHz radios don't need to be disabled but can provide value as monitor mode radios providing full-time intrusion detection, spectrum analysis, remote packet capture ability, and enhanced location tracking. However, these arguments have been less than convincing, with customers still feeling like they're not getting the value they're paying for (that perceived loss kicking into effect). And attempts at selling single-radio 5 GHz APs aren't really attractive from a financial perspective, because the cost of the AP is only minimally reduced compared to a dual-radio design.
More flexible AP form-factors will become more prevalent in the market to address the need for greater WLAN capacity, take advantage of more 5 GHz spectrum availability, and introduce ultra-high speed in-room performance with the 60 GHz band and 802.11ad. Some vendors have been playing with the technical feasibility of band-unlocked radios and multiple radios in adjacent bands within very close proximity (inside the same AP) already. This is tricky stuff to avoid interference inside the AP, requiring specialized skills and custom circuit board design. Not all vendors have the chops or expertise to pull this off, so we'll likely see the market share leaders drive this as a custom-designed and differentiated product initially, with smaller market vendors trailing once reference designs become available from ODMs (Original Design Manufacturers; many smaller Wi-Fi vendors don't actually design their own APs but take stock reference designs and tweak them if anything). I believe vendors will work all these complexities out, if they haven't already.