The same happened with Portuguese in Brazil, 'Vós Mercês', which is formal, is used throughout the country as (simplified) 'você'. And the informal form, 'tu', is rarely used (only in the South).
even in places and situations where 'tu' is used it's mostly still conjugated as if it were second person singular.
'EU BEM QUE TE AVISEI - TU EMPINOU ELE PEI'