During EA's latest earnings call last night, the publisher revealed details on a number of its forthcoming games – including the fact that Mirror's Edge 2 will be released in the first quarter of 2016 along with a sequel to Plants-vs-Zombies: Garden Warfare and news that Titanfall 2 won't launch until fiscal year 2017 (April 1st, 2016 to March 31st, 2017).
Despite this, EA offered no details on BioWare's forthcoming games, including Mass Effect 4 and their unannounced IP. The likelihood is that we'll get details on Mass Effect 4 during EA's E3 press conference on June 15th, and possibly a release window as well.
Both Mass Effect 3 and Dragon Age Inquisition were delayed and BioWare may do so again with Mass Effect 4. Given that EA didn't discuss the game during their earnings call, we probably won't see the game until fiscal 2017.
However, EA did state that they have unannounced games in development for release by March 31st, 2016 and there have been suggestions that a Mass Effect collection bringing together the first three games will be developed at some point. The fact that BioWare has openly spoken about the possibility has only helped fuel hopes for such a collection and if EA is launching in fiscal 2017 it seems feasible that they may aim for an autumn or spring release for the Mass Effect collection.
If there such a collection, hopefully BioWare will take a leaf out of 343 Industry's book when they included terminals in Halo: Combat Evolved Anniversary and Halo 2: Anniversary with teasers for what was to come in Halo 4 and Halo 5: Guardians respectively.
According to a recently leaked questionnaire, the next Mass Effect will be set in the Andromeda galaxy. BioWare has revealed some details about the game, including the return of the Mako and the game's focus on exploration.