There is obviously a huge demand for airlines. To me that implies that new airlines will appear when old ones go bankrupt. Since airlines don't own any infrastructure, I don't think much would be lost.
Yes and no. As we've seen with empty or mostly empty flights to keep an airline's spot at the gate, airports are a finite resource. If airlines go bankrupt, you're likely to see consolidation exacerbated by a barrier to entry, absent regulation and/or antitrust enforcement.