Okay, I've heard that the Dragon Knights of the Kingdoms theme are a remake of the Dragon Masters from the mid-nineties. is this true, or just speculation???
Any such connection is purely up to your imagination. I doubt the LEGO company would even remotely consider Dragon Maters when considering the new lineup. Besides, the Dragon Masters' prominent point was that they actually controlled dragons-- but there aren't any in the new Kingdoms sets.
As I understand it, LEGO themes these days are largely based on concept artwork-- they hire some artists to do some images of a castle-themed world, and they discuss and refine them gradually, eventually developing more and more what the theme will look like. While they may use inspiration to create that vision, I highly doubt that past LEGO themes would play much of a role.
However, fans have been imagining connections between LEGO castle themes for a LONG time. I remember seeing people's stories on Usenet posts from 1994, I believe-- back when Dragon Masters were still new! Back then, people had all sorts of theories about how the Dragon Masters evolved from the Black Knights, how they interacted with the Crusaders and Black Falcons, and so-on-and-so-forth.
The great part has been when LEGO has left little "clues" that connect the dots. Dragon Masters and Black Knights had similar oval shield designs-- Royal knights and Knight's Kingdom featured a very similar lion head. And Forestmen and Dark Forest had identical heraldry. I don't believe LEGO's ever intended them to indicate a particular storyline or connection. My guess is it's been about money-- they already have artwork and printing ready (maybe even leftover parts), so they re-use something older. But it's fun as a hobbyist to invent a storyline that uses these as "hints" as to what might have happened.
LEGO has never intended any "over-arching" storyline. The original sets were left intentionally vague to encourage imagination, although gradually each faction began inheriting distinctive characteristics (but no story). Since 2000, each castle subtheme has had its own microcosm of a story, that's not really intended to connect to other castle themes that LEGO has done. But that shouldn't stop you from imagining your own storyline.