The release of this trailer is great for Marvel AND for DC, no thunder will be stolen from them in 2 weeks once BvS is released.
I remember hearing from someone that DC wanted to steal Star Wars thunder because they released the teaser a day after Star Wars released that Teaser 2 at the convention. No, wrong. First, who can compete against Star Wars? Second, DC only wanted to capitalize on the high internet traffic DUE to Star Wars, as many other big movies did that weekend.
I'm sure Marvel would love it if DC succeeds, nobody gaining money from the comic book mania is interested in audiences facing comic book fatigue, Age Of Ultron declined a little bit(most domestic, increased worldwide) so If BvS is GREAT(and you bet your ass this trailer will be playing in front of BvS) it makes more people wanna see the next genre movie.
The only reason DC has put 600-800 million in the last two years to produce BvS, Suicide Squad, Wonder Woman(and very soon Justice League) is because Marvel CONVINCED the audiences that a shared universe is something that works, and is entretaining. So a chunk of their target audiences are very similar.