It is unlikely that a “new” drug will be developed in time. Even with lockdowns, most people will already have had Covid19 long before anything “new” is ready for commercial use (a concept sometimes called “herd immunity”). Remember that the figures such as those released last week by Governor Cuomo indicate that perhaps for every one person who tests positive for Coronavirus (and is usually only tested when they have symptoms), between five and ten others have antibodies indicating they already had the disease but didn’t get sick. Once the percentage of people with antibodies reaches a certain point (longer in lockdown areas, faster elsewhere), the need for a drug will decline.
Since the drug companies are using “old” drugs already approved for other purposes, their marginal costs are very low. Remember, the cost of drugs is not the actual manufacture, but the research to develop it. They already did all the development work and research and testing, and the drug has proven “safe” already (and effective for some purpose, not necessarily for Coronaviruses). The companies will anxiously offer drugs to doctors for free in the hopes that the drug will work against Coronaviruses, thereby enabling the company to start charging outrageous prices for the drug. Under existing law, the companies aren’t allowed to sell (especially at outrageous prices) a drug if they are promoting it for a use for which it has not been established as being “effective”.