Speaking strictly for NYC (the town I live + Airbnb host in), I think the more relevant metric is- what percent of Airbnb's revenue comes from the illegal kind of rental (i.e. rentals of the entire unit for more than 90 days of the year) vs the legal kind (whole-unit rentals totaling less than 90 days per year, as well as shared-unit rentals of any length)? According to Gothamist, 75% of its NYC revenue came from whole-unit rentals.[6] How much of that was legal is anyone's guess, but this is one reason why Airbnb was fighting tooth and nail to stop the recent city council legislation.[7]
NB- Another reason is that, once the city collects hosting data, it will likely use its housing inspection mandate to shut down most if not all Airbnb rentals in the city (not just illegal ones) at the behest of the local hotel employee's union. But that's me speculating, so take it with a grain of salt.
Keep in mind that Airbnb made $140 million in NYC in 2018[3], had $2.5 billion in 2017[4], and over $1B in revenue in Q3 of 2018 alone[5]. So the percentage of revenue it contributes is likely between 4-4.5%. If this went away overnight, the company would probably be fine as long as the damage ended there. But there's no guarantee of that, since other cities are considering similar legislation and are looking to see what the outcome of the above battle will be.
In the end, NYC will probably succeed in approving a permit system similar to San Francisco's, which will be enough to get the city the information it needs to shut down any Airbnb host it wishes.
[1] https://www.nytimes.com/2018/07/18/nyregion/new-york-city-ai...
[2] https://www.citylab.com/equity/2018/03/what-airbnb-did-to-ne...
[3] https://www.bloomberg.com/news/articles/2018-07-24/airbnb-s-...
[4] https://www.reuters.com/article/us-airbnb-results/airbnb-had...
[5] https://www.pymnts.com/earnings/2018/airbnb-third-quarter-re...
[6] http://gothamist.com/2018/06/28/city_council_takes_on_airbnb...
[7] https://ny.curbed.com/2018/7/19/17590164/airbnb-nyc-law-prop...