Do you see the DC Extended Universe eventually surpassing the Marvel Cinematic Universe both commercially and critically in the future?
Yes to critically. No to commercially.
It's possible that, critically, the DCEU will surpass the MCU eventually. Wonder Woman is one of the highest rated comic book movies so that proves they can do it. DCEU just keeps getting in the way of itself by putting the focus on a shared universe rather than the movie at hand. Their movies seem to be made with longing. Like they have always longed to make a good comic book movie since they're only ever heard of them through a rough description.
Wonder Woman shows they can do it. It was also the only movie that stayed true to the character and wasn't completely focused on building the shared universe. They have the cast, they have the source material, now they just need to hire the right people to create the movies and stay out of their way. If they do that then yes, they could surpass the MCU critically.
Commercially surpassing the MCU?
Even if their individual movies start making as much as the bigger MCU films, they have a long way to go to catch up. Marvel has become the standard for super hero movies. Movies are anticipated years in advance and each one builds to the next one while being entertaining in it's own right. DCEU movies don't have anywhere near that level of anticipation with the general movie going public. I'm just talking about releases within the same year from each studio matching each other dollar for dollar. If we're looking at lifetime then the MCU is so far ahead even the Flash would have a hard time catching up.
Let also not forget that within the next few years the MCU will be welcoming their versions of Fantastic Four and X-Men into theaters. Those movies, especially the first MCU X-Men movie, could rival Black Panther as far as the gross goes. Marvel has stuck with a three movie per year formula for several years now. The X-Men have released one–two movies a year on their own. I wouldn't be surprised if the MCU starts releasing four movies a year once the rights are all squared away.
So you have a history of higher quality films with several highly anticipated releases within the next few years for the MCU and a lot of uncertainty and apathy for the future DCEU films. That doesn't make me think they'll catch up.