If aircraft are truly flying their business trajectory developed entirely for their particular weight and cost index against the weather winds and temperatures to make a particular approach time, it is extremely unlikely that they will be closely following another aircraft in the way they can in the current North Atlantic organized Ocean Track Structure. SLOP has just as much chance of putting you behind another aircraft as flying your business trajectory. It is expected that there will be possibly significant dispersion of ocean tracks add in the use of ADS-B (possibly satellite sensed by the controllers) and the unstructured 'free routing' of the FABs will continue out over the oceanic airspace at least the European and Canadian controlled airspace possibly with almost en-route levels of separation.
With everyone 'following the favorable winds' there will not be opposite direction traffic, there could be crossing traffic but that will be separated by its trajectory from your trajectory. Sitting in the continual chop from an aircraft ahead will no longer be an issue. Emergency descents similarly should just be straight ahead as offsetting is as likely to find another 'user preferred trajectory' below you. TCAS, CDTI and controllers with ADS-B surveillance will become important in cases like that..