I think a large part of it is that after around 10 years of dominating Starcraft 2 and 20 years of dominating Starcraft 1, there are now some European players who are repeatedly beating Korean players (and everyone else) in the big tournaments.
(Including in-person tournaments, so you can't chalk it up to latency differences. Though of course there haven't been any of those in the past year, so we'll see if that'll be sustained.)
The two main usurpers, Serral (Finland) and Reynor (Italy) also have a really entertaining rivalry. I'd go so far as to say that those two may have single-handedly kept professional Starcraft 2 interesting and alive.
I think the uptick in challenge youtube videos is also no coincidence. These are games where there's depth in terms of acquirable skills, and there's definitely interest in the community for displays of mastery in these types of games.
(SC1 was actually the first computer game I ever played, back in 2000 or so, which I think is why it still holds a special place in my heart. Funny to think "computer game" is kind of an antiquated term now.)
ASL looking strong in Korea.
If there's one business lesson to take from the history of the video game industry, it's that being a video game company is extremely unreliable. Being a collectibles company is much more reliable.
As the company leaders look for ways to make their business endure, it's natural for them to turn to more reliable business models.
Nobody likes layoffs.
On the other hand, Mario keeps reinventing the adventure genre with creative mechanics, even though storyline/CGI of each new game is basically non-existent compared to Blizzard's capabilities. WoW obviously did very well in spinning the Warcraft lore into new directions, and Starcraft Ghost was also highly anticipated before the vaporware lost its steam. I think the main difference between Nintendo and Blizzard - and why Nintendo still commands such strong brands - is Nintendo plays the long term game, never getting drunk on a single unicorn success.
Paradoxically, I've noticed an uptick of new creative Starcraft 2 content on Youtube (similar to those "can you beat the game by doing [insert crazy premise here]" types of videos you see in the Mario community).
I think the two company direction things that were noticeable for me were that they decided to try to embrace two major cop-outs: milking cash shop (skins, voice packs) and trying to pull Disney-like re-runs of classics (SC and WC remastered). Many in the community are lamenting that e.g. the dev team behind Starcraft is essentially disbanded. It's like they fundamentally gave up being a game company, and decided to be a collectibles company instead.