Something like this?

WITH SampleData AS(

SELECT 'DANIEL SHAFFERS, INCORPORATED.' AS CompanyName UNION ALL

SELECT 'BUFFETS, INCORPOR. ' UNION ALL

SELECT 'WAYNE, Incor ' UNION ALL

SELECT 'STARK, Incorp. ' UNION ALL

SELECT 'Osborn, Co. ' UNION ALL

SELECT 'Inception Industries '

)

SELECT CASE WHEN CompanyName LIKE '%,%Inc%'

THEN LEFT( CompanyName, CHARINDEX( ',', CompanyName)) + ' Inc'

ELSE CompanyName END

FROM SampleData