Update: an official version of the new trailer has been embedded below.
Marvel vs Capcom: Infinite had another airing during ESPN2's broadcast of the Capcom Cup, this time to reveal two new characters. In an announcement that won't surprise anyone with a passing interest in the series, Captain America and Morrigan will join the ensemble. They join Iron Man, Captain Marvel, Ryu and Mega Man X.
Infinite was announced at Sony's PlayStation Experience event at the weekend, which was followed by the airing of its first gameplay demo at the Capcom Cup on Sunday. Mat Paget has written at length about both the announcement trailer and the gameplay video here and here, and he sounds very excited about it. Marvel has confirmed that it's definitely coming to PC.
I'll update the story when better images of Morrigan and Captain America become available. In the meantime, here's a capture of the ESPN2 stream, courtesy of YouTuber MaglioWow (skip to the 50 second mark for Captain America and Morrigan).