Hey i wish i had good news for you but unfortunatly my time is being stretched very thin right now. I'm going to be as honest and upfront as possible. i'm working on 4 different projects. (5 including this one) and being a one man indie developer means i have to prioritise. There is one important thing i'm working on that will be done sometime early October, that currently is using up all of my time. After that the other things are quite small so i can put more work into Dungeon Maker Sketch and the other projects.
If i had to give you a time frame: Late October - early December this year there will be an early release of the new version (It will be early access type thing alongside the old version). I have it started and i'm sure you'll love what i have planned for DMS and it's being rebuilt from the ground up with better artwork, UI and more features. Then around March-April 2021 should be the first 1.0 release of the new version.
Sorry that i don't have better news. I'm sure everyone understands that this year has been difficult. When an update is approching i will be posting on here screenshots and sneak peaks and over on the Disord server. The best i can say right now is sit tight, an update is coming.