Sure, but business travel only accounts for 1.5% of GDP. And it's pretty unlikely that it permanently falls by more than 50%. Then you have the fact that if company's spend less on business travel, they'll have more to spend on other things. In particular expect to see products like Zoom and Slack get much more spending as virtual meetings become the norm.
Finally even if business travel falls, expect consumers to make up a lot of the reduction in demand. The capacity exists and isn't going anywhere. Those airline seats and hotel rooms aren't going to sit empty. The price may fall, but tourists will take more trips when given discounts on the prices they're used to.
In general you can extend this reasoning to most of the pessimistic scenarios. First, real productive capacity will still be the same after the quarantine as it was before. Second, money spent in some sector isn't just going to get thrown into a hole if people stop consuming those products. One industry's loss is almost always another industry's gain. Finally, when demand contracts that means falling prices. When prices fall that enables new consumers and business models in the market.
In Europe many industries, including air travel are at or over capacity. Airlines operate at razer thin margins. We might see some consolidation in the market which could decrease the overhead costs, but not by much. There is simply no room to decrease prices that much. And there is not much evidence that the demand is very price-elastic either. Air travel has more competition by other forms of travel with less safety restrictions, less climate impact stigma, etc.
Finally even if business travel falls, expect consumers to make up a lot of the reduction in demand. The capacity exists and isn't going anywhere. Those airline seats and hotel rooms aren't going to sit empty. The price may fall, but tourists will take more trips when given discounts on the prices they're used to.
In general you can extend this reasoning to most of the pessimistic scenarios. First, real productive capacity will still be the same after the quarantine as it was before. Second, money spent in some sector isn't just going to get thrown into a hole if people stop consuming those products. One industry's loss is almost always another industry's gain. Finally, when demand contracts that means falling prices. When prices fall that enables new consumers and business models in the market.