What if we don't have trusted decision-makers to conclude our Dotmocracy process?
Traditional elections could work, but are more likely to reward those whom are charismatic rather than those whom are wise, and may lead to cliques and destructive conflict within the group.
Another method might be to recognize which few people have authored the most more popular ideas and get them to form a committee.
Or use a lottery to select a handful of random members to serve as an appointment panel that will interview applicants and select an executive committee to serve as the trusted decision-makers.
Or your could use some form of recommendation system to recognize whom among the group is most trusted to make decisions. This is more complex then simple voting or rating of candidates. See Meritocracy in Wikipedia.
Alternatively, you could force your group to continue the Dotmocracy process until a single complete and popular proposal becomes evident and most folks are not interested in generating or reviewing any further ideas, but this is likely to lead to exhaustion, frustration, and potentially superficial and unsophisticated decisions.