The products that still trade predominately {OTC, bilateral, non-electronic} do because non-price factors, trading conventions, and counterparty risk make it difficult or impossible to trade on a central exchange. Expressive Bidding and a mechanism that allows for matching market dynamics (OneChronos) will enable electronification and more active trading in these markets. Ten years ago, I would have said that there were commercial headwinds against this (dealers wanting to trade bilaterally). With banks increasingly focused on repeatable and less variable trading revs, such is no longer the case. The unsuitability of such products for double auctions is the limiting factor.