Compare that to American comics which is dominated by superheroes and animation which is dominated by comedy.

Hey, I'm a man and love SD, know other men that like it (it even increase basketball practice in Japan several fold)... but yes, perhaps there are a lot of women fan...

But to call SD battle shonen is bizarre.

One of your links is from 2009, another is an old man grumbling about animators, and another actually begins with the line, "The anime industry, while not as strong as it was back in 2004-2006, is still booming."

The simple fact is that anime is growing, mainly due to overseas interest.  

https://www.animenewsnetwork.com/news/2018-04-30/anime-industry-report-shows-continued-growth-in-overseas-market/.130302

"Total revenue from overseas sales, which includes broadcast rights, box office, DVD/Blu-ray sales and merchandising, jumped almost a third to $6.79 billion (￥768 billion) over the previous year. Sales to China increased, an AJA spokesperson confirmed, but figures for individual countries aren't compiled for the report."

https://www.hollywoodreporter.com/news/japans-anime-industry-grows-record-177b-boosted-by-your-name-exports-1058463

The decline you're talking about doesn't exist.  There certainly are problems but there have always been problems.  The outlook, however, is positive.

As far as your idea that Japan needs to change anime to suit the rest of the world, we've already seen that with the gaming industry and it was a failure.  The Japanese gaming industry only began to recover when they stopped trying to copy western trends and returned to doing what they knew best.

Regarding your remarks on diversity, I still get the impression that you're talking about a subject where you know little.  Does anime have big name titles designed to appeal to key demographics?  Of course.  However, saying this means it lacks diversity would be like pointing to a select group of Hollywood movies and pretending nothing else was being produced by the film industry.  Anime pulls from sources designed for little girls, little boys, teenage girls, teenages boy, mature women, and mature men.

Is anime anywhere close to being diverse as manga?  No.  Is it more diverse than western animation?  Yeah.  It typically hits several different genres that are intended for different demographics.

Let's take a look at some of the best anime of last year in visual form:

Not diverse enough for you?  Okay, that's fine.  "The same shit"?  It would seem that you're talking about a subject where you know very little.

Theres comics outside of marvel like :
darkhorse comics that do evil dead /army of darkness series ,star wars , terminator, robocop, conan, aliens or aliens vs predator ,overwatch , halo, starcraft,
IDW for My little pony , adventure time , Transgormers, Sonic ,
Archie comics that does Jughead, Megaman ,merry christmas.
Dynamite Entertainment comics does Vampirella,Jungle girl,Red Sonja,Robot princess,Battlestar Galactica
Many more etc etc

Did you read Will Eisner, Crumb, Harvey Pekar, Maus? Maus won a Pulitzer. Vertigo ? Alison Bechdel? She won the NY Times nonfiction award, man. Everything is American comics. We talked about mainstream comic books , Japanese and american it was limited. All comics have genre and are diversity, but what is bringing money, real money in shonen jump is a One Piece, was naruto in its time, etc. A cut in the Marvel / DC universe to say that American comics is limited is not knowing the same. Not knowing that it has a lot of horror comic, fantasy comic, cover and sword, independent etc. Sometimes one of them can reach a large audience, as with Japanese comics, but what supports the market, at least in Japan, is shonen, battle-oriented and humorous, not unlike American superheroes and comedy cartoons.