At this stage of the game for the EU region, I'd try to identify potential impediments for the three VB's remaining - July, August & September. As I see it, these could possibly result from two specific areas of concern: a) hard Regional Limit and b) Regional Diversity Objective.
Ad a): the regional limit for EU is not published, yet we confirmed in DV 2014 that it does exist. You only know once it has hit you, as occurred in September of last year, when the number remained at 40,150, as previously announced for August. The 19.5K number you referred to is simply an internal calculation from this forum, not an official number.
Ad b) Beyond giving out 50+K DV Visa/Year KCC has to maintain Regional Diversity as key objective, as defined by law. With the other two large DV regions, Africa and Asia, in serious trouble this year (due to different reasons, yet this is another subject altogether), KCC has to ensure that EU won't eat the cake by its own and, doing so, messes up diversity targets between the DV regions, set in advance. This is separate from the above-mentioned pre-set hard limit - here the current lack of progress in other regions would impact Europe, i.e. Africa and Asia will have to be given the chance to catch up.
Therefore, in terms of potential impediments for EU participants with high CN's: there certainly is a possible scenario in which Europe will progress by approx. 2,000 - 4,000 for each of the coming two VB's, July and August, and then may remain at this same number for September, meaning that no additional interviews may be scheduled at EU US consulates during that final month of the DV 2015 year. Makes sense?