count with and without filter

PowerBeeEye 

For your count with service you don't need the calculate.

Count with service = DISTINCTCOUNT ( 'Table'[SystemName] )

Then we can use that one and some filtering to calculate those without the selected service.

Count without service = 
CALCULATE(
    DISTINCTCOUNT('Table'[SystemName]),ALLEXCEPT('Table','Table'[Company],'Table'[forest])) - [Count with service]

This counts the total number of systems for the selected [Company] and [Forest] using any service the subtracts the count for the selected service leaving us with the number not using the service.

My sample file is attached for you to look at.

PowerBeeEye 

That was an interesting one.  This should get you what you are looking for.

Systems without service = 
VAR _Systems = VALUES ( 'Table'[SystemName] )
VAR _AllSystems = ALL ( 'Table'[SystemName] )
VAR _Missing = EXCEPT(_AllSystems,_Systems)
RETURN 
CALCULATE ( 
    CONCATENATEX ( 
        VALUES ('Table'[SystemName]), 'Table'[SystemName],", " ),
        ALL ( 'Table'[ServiceName] ),
        'Table'[SystemName] IN ( _Missing ) 
)