Why do we need to read between the lines?
It is clearly mentioned that "You will be able to at least maintain current club Vistara status or get upgraded if you qualify based on cumulative points" - So it clearly states that Vistara Gold --> AI gold or Vistara Silver ---> AI silver
Co branded cards is a totally different topic on which clarity is yet to emerge, but once you get Gold via Co branded card, status remains for one year and it has nothing to do with Co branded card once account is upgraded