The same basic tech can't be tuned forever. Is like saying that a tuned up Intel 8088 could be on par with todays Core i7 if they went on tuning the same original design. About sensors, there is a lot going on, under the tech point of view. Better manufacturing process along with totally new technologies (organic sensors ahed of everything else) will bring tremendous improvements in few years from now.
In the meantime, we are witnessing great advancements that are bringing small sensors (like the one in rx100 ii and in the latest m4/3 high end models) to offer similar dr to bigger ones.
I'm quite sure that samsung has something very imteresting in the pipeline. But first, they probably had too many 20mp sensors in the warehouse, so decided to stick with that for another product generation.
So here is the thing, A sensor isn't a processor.
The goal of a Sensor is to replace film.
Megapixels start giving diminishing returns at a certain point. The current NX sensor is actually very good, if I showed you 6 actual pictures you'd be hard pressed to tell me what sensor they were shot on.
New tech is nice and all, but a mature sensor has many advantages like improving the quality of the ISO and lowering production costs. Glass is often more important then sensor. And the DR of most sensor is perfectly fine, people look for greater DR or better ISO because they aren't great photographers. I know my camera has limitations, just like any camera. ISO 6400 is insane, with f2/2.8 lens you shouldn't need more in most conditions, yes sometimes a fast moving child is an issue... that is why you get a flash.
Look at the PS3, came out as a big bulk box high price, low storage capacity. Finished it's live cycle very much smaller, cheaper with a higher storage capacity.
Sensors can have a similar life cycle. Better ISO, more efficient power, better heat, these minor improvement increase the effectiveness of the camera. You may not upgrade from one sensor version to the next but that is because unless you are a gear head you aren't going to anyway.
One of the nice things with hanging out with working photographers is you see them shooting with a D300 and then picking up a D610, or Shooting with a D90. Upgrading isn't the most important thing.
For me I'm looking to build my kit. I want a second body, the NX30 is a good replacement/addition for my NX20 and I compare it only to the NX20 in he same way I don't compare a D300 to a D5300. Even though the D5300 has a newer sensor they aren't the same class of camera. I also want lighting gear, lens, and accessories. I may actually break down and pay the $600 the new Samsung flash is likely to cost because having a ttl flash that can work off body in commander is handy.
I care only about what tools I want in my box to do the jobs I want to do. If Samsung can't do it, I'll switch systems, I'd just prefer not to, and right now Samsung bought some time, the NX30 on paper meets my needs well enough that so long as the buffer isn't complete diaper stink I'll likely start picking up some of the lens I'm missing.
