GameSpot describes as a "reputable source." EA refused to comment on "rumor and speculation" to GameSpot, but the site says EA's option to secure the rights was based on the first game's sales performance.
Polygon backs the claim EA secured the rights to a Titanfall sequel, adding that according to its sources the game won't be a Microsoft exclusive. EA is only releasing Titanfall on Xbox One, Xbox 360, and Windows PC.
While EA is refusing to comment and the sources' claims aren't confirmed, the bits and pieces we've heard from EA and Respawn seem to back up the speculation. Respawn co-founder Vince Zampella already assured fans that his studio will make games for the PS4, just "not the first Titanfall." EA Chief Financial Officer Blake Jorgensen previously said, "I'm sure that there will be future Titanfalls at some point that may be on multiple product platforms. [I] don't know, that's up to the teams that are going through that now."
In any case, the Xbox 360 is still waiting on the first Titanfall. The Bluepoint-developed version was due to hit the platform on March 25, but EA delayed it yesterday to early April.