The current proposal doesn't change the 15 minute thing, so whatever effect you think it has should already be in effect, no?
Currently we have pretty much complete system wide failure as the vast majority of active SP are just winding up back into the staker's pocket via some form of content indifferent voting (self voting vote selling).
The 15 minute timer has an effect on the issue you're raising: the mobility of votes when it comes to established authors. Currently, the focus is on avoiding the near complete failure of votes to reflect content on any level, which it doesn't have too much of an effect on.