Dynamic Table in DAX for Bin

Not sure I understand all the requirements, but let me give it a try.

1) Create a calculated table (should be a disconnected table) which will have an extra row for Other. This is the column which will be used in the chart.

ProdSubCat_List = UNION(VALUES(ProductSubcategory[Product Subcategory Name]), 
ROW("SubCategoryName", "Other"))

2) Create a measure

NewSalesMeasure = 
VAR SelectedSales =
    CALCULATE (
        [Sales Amount],
        INTERSECT (
            VALUES ( ProductSubcategory[Product Subcategory Name] ),
            VALUES ( ProdSubCat_List[Product Subcategory Name] )
        )
    )
VAR AllSelectedSales =
    CALCULATE (
        [Sales Amount],
        INTERSECT (
            VALUES ( ProductSubcategory[Product Subcategory Name] ),
            ALL ( ProdSubCat_List[Product Subcategory Name] )
        )
    )
VAR AllSales = CALCULATE (
                [Sales Amount],
                ALL ( 'ProductSubcategory'[Product Subcategory Name] )
            )
RETURN
    IF (
        HASONEVALUE ( ProdSubCat_List[Product Subcategory Name] ),
        SWITCH (
            VALUES ( ProdSubCat_List[Product Subcategory Name] ),
            "Other", AllSales - AllSelectedSales,
            SelectedSales
        ),
        AllSales
    )

 3) Create a column chart with ProdSubCat_List[Product Subcategory Name] on axis and NewSalesMeasure on values. Put a slicer which has ProductSubcategory[Product Subcategory Name] 

 This should work

Update - 3/1/2017 I blogged about this here - http://sqljason.com/2017/03/dynamic-grouping-in-power-bi-using-dax.html

I have also optimized the formula in the blog, in case anyone is interested