As far as I’m aware, a proper “impasto” engine for Krita may be one of the more difficult new features to implement. In the meantime, (This experimental feature being developed) should cover for most impasto effects. The goal should be to eventually be able to emulate the impasto effects seen in many Van Gogh paintings when using Krita to paint.
The main difficulty I’m aware of that might occur when implementing this feature is the issue of translating the behavior of the impasto engine to older brush sets that don’t use the inpasto engine. There might be the issue where the paint depth remains intact when colors are blended with older smudge brush presets.
As far as new features for Krita in the future, this one seems to be lower priority, but one I’d love to see properly implemented a few years down the road.