Probably going to release Resistance/RE3 at a similar time to avoid backlash.
It's what Blizzard should have done with Diablo Immortal. People wouldn't have been so upset if they announced Diablo 4 at the same time.
LTD: PS4 - 125m, Switch - 110m, XBO - 51m
2020: PS4 - 9m, Switch - 22.5m, XBO - 2.5m, PS5 - 4.5m, XBX - 2.8m