If the event is cancelled by the city or other government body there is probably event insurance which is triggered which can pay for refunds. Events like this,

If the event is cancelled by the city or other government body there is probably event insurance which is triggered which can pay for refunds. Events like this, even ones with lots of sponsorship and corporate interest, do not usually have high margins. As a result, any cash they have right now is needed to pay their suppliers. I doubt they have money to refund more than a fraction of tickets. The responsible thing is for the local government to cancel it. Ideally SXSW would make this decision but ultimately they are not public health experts.