Future dated forecast

Hi, msa_007 

You can try this measure to solve your need.

Rate of Decrease = 
VAR _FirstValue =
    CALCULATE ( MAXX ( VALUES ( 'Date'[Date] ), [Measure] ), ALL ( 'Table' ) )
VAR _LastValue =
    CALCULATE ( MINX ( VALUES ( 'Date'[Date] ), [Measure] ), ALL ( 'Table' ) )
VAR _dayDiff =
    CALCULATE ( DATEDIFF ( MIN ( 'Date'[Date] ), TODAY (), DAY ), ALL ( 'Table' ) )
VAR _valueDiffBefore = _LastValue - _FirstValue
VAR _decrementalValue =
    DIVIDE ( _valueDiffBefore, _dayDiff )
VAR _daysFeature =
    DIVIDE ( _LastValue, - _decrementalValue )
VAR _endDate =
    TODAY () + _daysFeature
VAR _dayDiffAfter =
    DATEDIFF ( TODAY (), SELECTEDVALUE ( 'Date'[Date] ), DAY )
VAR _dayAddDecrementalValue =
    IF (
        _dayDiffAfter > 0
            && _dayDiffAfter <= _endDate,
        _LastValue + _dayDiffAfter * _decrementalValue
    )
RETURN
    SWITCH (
        TRUE (),
        SELECTEDVALUE ( 'Date'[Date] ) <= TODAY (), SELECTEDVALUE ( 'Table'[Value] ),
        _dayAddDecrementalValue
    )

Best Regards,
Yang
Community Support Team

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