My main point was that the WT may be playing with fire here. Boring and ineffective as door to door ministry is, it has been a tried and tested method for keeping JWs active in the faith for over a hundred years. Sociologists have argued that the function of JW door to door ministry is more about maintaining commitment of existing members than about recruiting new members. See: Munters, Q. T. “Recruitment as a Vocation: The Case of Jehovah's Witnesses.” Sociologica Nearlandica 7 (1971): 88-100.
So by substituting cart witnessing for traditional door to door preaching the leadership might not only fail to gain new members. They may lower the morale and eventually the numbers of current JWs who are willing to preach and remain active. They may have underestimated how important traditional door to door ministry has been in structuring JW life, self-understanding and commitment. Over emphasis of cart witnessing threatens to undermine that.