I've only been dancing for 10 months so obviously I can't comment further back than that, but what I have seen in that time is a wide difference in abilities amongst teachers when you travel around.
All of my local teachers are of roughly the same standard (with one notable exception, who was just not born to teach, although she CAN dance!), which is good for consistency.
On my travels I've come across some awesome teachers elsewhere, but naturally they tend to stay on their home turf or travel to the most popular venues.

But to get to the point, recently I've seen some of our local teachers starting to teach some of the more detailed techniques that I've seen taught elsewhere and the franchise owner is introducing concepts seen elsewhere but up until recently ignored in East Anglia.

But are they getting better? just trying to copy teachers from elsewhere? responding to the needs of their audience? not sure, but they are changing.