I reckon it's become the most non-descriptive and often misused term on the scene, Chalks, (along with 'Crossover' of course ).
The definitions seem to be so subjective and personal these days.
The term Modern Soul has certainly lost any true and broadly accepted identity.
The descriptions, I see on here, tend to fall under the following:
Definition 1 - Modern Soul - Recently recorded Soul Music.
Definition 2 - Modern soul - All Soul Music recorded after 1969 up until today.
Definition 3 - Modern Soul - Any Soul Music from the 70's and Early 80's played on the Northern Scene.
Definition 4 - Modern Soul - Not Northern.
Definition 5 - Modern Soul - Disco.
There may be other interpretations, but those tend to be the main ones.
Sean