The post on Mrdots blog was from 31.12.18, promissing new content, Jeff's post was from 4.1.19. Change of mind in 5 days? This would be a huge kick in the balls of their fans and supporters. That tells me, that Jeff is likely not that informed than you might think.
"New content" isn't the same as "Chapter 3", is it?
You seem to be confused on the distinction between "a Chapter" and "an update', in this context.
Every update due for 2019 is still part of Chapter 2; the intent is to finish Chapter 2 (possibly this year, though maybe next, if a satisfactory conclusion would require more than 4 updates), but once Chapter 2 is done, there will be no Chapter 3.
A third Chapter was originally intended, but after the whole Patreon debacle, it was decided that it was an untenable goal; hardly surprising, since at the current rate of development, the third Chapter would likely not be completed before mid-2024 (Call it 14 total updates, at a rate of 4 updates per year, starting at the earliest early 2020).