So this is good news, anyway - previously, the Iranian government had set a fixed “official” exchange rate against the US dollar that was way lower than the market rate, and citizens were totally unable to convert their savings out of the (badly hurting) rial while well-connected government officials made an absolute killing off of buying US dollars at market rates and selling at the official rate. Now at least people with savings can get out of the rial before it loses all useful value.
Not sure what’s going to happen as the sanctions seriously impede the Iranian government’s ability to transact ordinary business - because really their economy wasn’t doing so well to start with, with high unemployment and many sectors dominated by corrupt state-owned enterprises and the children huge population boom now entering working age with zero employment prospects.
As long as oil prices are high, the government can afford to keep up its massive social welfare programs and subsidize consumption for the huge number of unemployed young people (around a quarter of the under-24 population is unemployed and that is ticking upward). If oil prices fall, or if sanctions start having sufficient bite that Iran can’t easily accept international payments, then serious difficulty is going to arise.