Difference between OpenLayers 5 and OpenLayers 6

Question

Quick question regarding upcoming release of OpenLayers 6. Does anyone know what are the main differences between OpenLayers 5 and OpenLayers 6. I read something here but additional questions arose:

1. Is it true that OpenLayers 6 will be complete rewrite of library or some of the existing functionalities such as layer rendering and WebGL?

2. Will it be possible to easily transition from 5.x.x to 6.x.x ?

3. Also could someone explain upcoming Vector Tiles implementation what this means for the end user (in short if possible)

4. When is planned release of Openlayers 6. According to online resources first, initial release was planned for the end of February 2019. Does anyone have info on new date?

That is it for now:) Thank you for your time and patience :)

Answer 1

Here is the change log (upto v6.0.0 beta 11) https://github.com/openlayers/openlayers/blob/master/changelog/upgrade-notes.md It's not a full rewrite and most of my OpenLayers 5 code works with OpenLayers 6 with minimal changes (such as postcompose to postrender the y coordinate in a custom tileUrlFunction and replacing ol.inherits). Don't expect the main release until these issues have been resolved https://github.com/openlayers/openlayers/milestones/v6.0.0