I see some people saying that this means Playstation is getting ready for PS5 "sooner rather than later". Okay ... sooner than? What? 2021? That was never even on the table.
To me this does not signal some kind of 2019 release, or even a 2019 reveal. We still have Days Gone and Dreams ... and while many would argue that The Last of Us 2 and Death Stranding will be cross-platform releases, given the fact that both were announced in 2016 and are closer to completion I really would assume a remaster for both is much more likely.
Something like this makes sense, I think:
Q4 2019 - TLOU2, possibly Death Stranding release
Feb 2020 - PS5 announcement, possibly Death Stranding release
E3 2020 - huge blowout
Holiday 2020 - release
If I recall correctly that's basically how the PS3 ended it's run and how the PS4 was announced