User blog comment:Dragonzzilla/ME3 Multiplayer DLC I Ideas/@comment-4967682-20120430002056/@comment-4950455-20120430003442

It's canon that they still exist, and they were planned to be included in multiplayer as one point, so why not?

Technically, what we have is a reference to "Collector swarms". Could mean swarms of Collectors, could mean seeker swarms (which are probably originally Reaper technology).