Re: errr...another possibility exists...
Nice try but this is *vanishingly* unlikely.
Though the cloud layers on Venus are indeed Earth like in some respects, on our own planet even the hardiest extremophiles can't tolerate the heat, pressure AND acidity at the same time.
Even the ones around black smokers have their limits.
I would suggest that its more likely that life started independently on Venus and adapted to the changing conditions, eventually going airborne as the oceans started to evaporate.
As a certain gentleman on a film once said, "Life WILL find a way"
I've also theorised that life might exist using heavy metals as DNA "bases" where normal DNA is merely a stepping stone and this though very unlikely isn't impossible in the complete absence of oxygen.
Some quirk of nuclear physics might permit isotopes to selectively leach out of the rocks so we just don't know what is really possible.