For roughly the past decade, Marvel (Disney, in all honesty) has created a composite "Monopoly" on Superhero films, revolutionizing the scape of mainstream comic media. They took what was nerdy and made it "cool" for the general audiences. Hats off to them for that. However, we wouldn't appreciate what's beautiful if it lasted forever.
Many critics and fan bases will disagree with the following statement: The DCEU will become more successful than the MCU after 2020.
Now before you leave me with 3rd degree burns in the comments let's go over the facts...Or rather a rather perplexing question: What comes after Infinity War?
That was rhetorical, and it is because the answer is practically nothing.
If we know one thing about the movie industry it's that the consumer base must be fed for a franchise to thrive onward. It's why companies like BV under Disney, Universal, Legendary, even Warner Bros. have been so successful for so long. Every single MCU movie is warranted and backed by a comic whether it be a spin-off or cannon. That's not the case with these other film producers. Disney doesn't need approval from a graphic novel to "imagine up" it's next signature princess, but Marvel does. That goes for DC as well. Every time a director veers off cannon(except for Chris Nolan and his outstanding Dark Knight trilogy), they get the brunt of bat(no pun intended). For example, Batman, in the new Dawn of justice, kills. The consequence? Zack Snyder getting trashed as a terrible director. Did he deserve it? No. Absolutely not. BVS was visually stunning. But breaking Batman's golden rule was indeed a terrible idea. Die hard comic fans don't see that side of the spectrum, and the question is whether pissing off your main fan base is worth the appeal to the general public. Now don't me wrong, I'm not saying DC is better than Marvel or vice versa, but I am suggesting that Marvel had its fair share of the spotlight and now DC will share it if not steal it. This assertion is more based on timing than content. It's more based on business strategy than the better production studio. As aforementioned, Marvel has ruled the scape for a long time and 2020 is when it's reign ends. Getting back on topic, let's take a look at what Marvel has to offer once the Mad Titan gets what's coming for him. An inhumans spin-off? I gagged watching the TV show trailer, a movie will make nominal improvement. Planet Hulk with a World War Hulk follow up? It's plausible, at the expense of consumers seeing all their favorite superheroes slaughtered at the hands of Banner. The bottom line is Marvel will be working with scraps. Guardians of the Galaxy came out of nowhere and turned into a big hit. No one knew who Star-Lord was before GOTG. But the success rate of GOTG type spin-off films is not reliable or feasible in the long term for Marvel.
The DCEU on the other hand, whether by accident or on purpose, has been waiting it out, and is just now gathering it's best material. Nolan's TDKT and other DC based productions kept us interested and waiting for the launch of the DCEU, a counter to Marvel's domination in the superhero movie scape. The DCEU is just getting it's roster set. Big names in Cavill, Affleck, Gadot, and Momoa are going to kickstart the extended universe no matter how bad Zack Snyder directs. We've seen flashes(no pun intended) of Darkseid, rumors about Brainiac, Dwayne Johnson hinting at Black Adam etc. And with Wonder Woman, the DCEU is shifting into overdrive. JL looks over the top on trailer; loaded cast, amazing effects, canonical arc, etc. Remember the box office haul the Avengers had? The JL movie will top that and may even top a few other Buena Vista productions (Frozen).
The conclusion is, the MCU is dwindling out after 2020 and DCEU has enough material, funding, and fan base to rake mass profit moving forward.