Will most likely not get an definitive answer to this as it is a bit of a how long is a piece of string question. In theory... the gap between 1.9 and 2.0 should be a lot shorter because if not all of the rework tasks are going to into 1.9 (endlings, visuals, mini games...) Dr.Muramasa previously hinted at 2.0 being mainly focused on correcting/beefing out the Anna story, making QoL changes (this might have now and been brought forward into 1.9) and getting all the stuff ready for the Steam release (additional character and questline.) Though Kal's development cycle changes like the weather, so expect anything really 😅
The first hints of what 2.0 should look like and what to expect will normally be posted in Planned Features and Content a couple of weeks after 1.9