Most likely 10nm is doing just fine. The problem is that 14++++ is too good. So They Are getting quite good yealds From 10nm. But 10nm does not get as high speed as old 14nm does. So datacenters and laptops goes to 10nm in this year, because electricity usage is important. But desktops remain 14++++ proses because it is faster than new 10nm. By 2021 They hope than 10nm is near as fast as their 14+++ is now.
My bet is that Intel is prioritizing whatever likely limited 10nm capacity it has for higher-margin products than mainstream CPUs such as its 10nm Agilex FPGAs. This would explain why the allegedly leaked roadmaps don't have mainstream 10nm until 2022: most of the 10nm production until then is going elsewhere and once Intel gets 7nm into production, high-margin products will go 7nm while mainstream will get migrated to freed-up 10nm fabs.
Almost like Intel is planning an exit strategy from mainstream PCs, relegating them to secondary if not tertiary priority.