Is the gap between Northern hemisphere and Southern hemisphere narrowing?
Can't see any evidence for that really. The southern hemisphere sides treat the autumn international as a useful development opportunity as they prepare towards the world cup. There have been plenty of years where northern hemisphere sides have done well against the southern hemisphere in the friendlies that are the autumn international. Once the real stuff, the properly competitive world cup, begins things revert to normal.
So in the equivalent cycle before the last world cup, in the autumn international of 2014 there were 6 victories of northern over southern hemisphere sides - fast forward a year to the real stuff and the final 4 in the world cup - New Zealand, Australia, Argentina, South Africa, each beating northern hemisphere sides in the quarter finals.
Let's not forget that despite all those autumn international victories by northern hemisphere sides in the autumn international the last time a northern hemisphere side beat one of the big 4 southern hemisphere side (yup 4 not 3, I include Argentina) in the sharp end knock out stages of the world cup was the 6th Oct 2007 - over yup 11 years ago.
