Seems there will be some rules and structure going forward for post Death Metal DC, while everything will be in canon.
DC could however for example do : one of Supermans book is set on pre crisis Earth 1 while Flash is modern Flash in his own universe in his own book. I guess crossovers could be multiversal.
Or maybe not, just speculation.
Some titles will be relaunched, some not, also new books launched but also less books. I guess JLD and Legion and whatever else could be replaced.