The airline industry got a $58 billion lifeline in the coronavirus federal aid package. But the path is unclear for these companies, whose operations and prospects will be forever changed by the global pandemic.Why it matters: People may want to minimize travel for the foreseeable future. Investors, analysts and industry watchers are trying to determine how much airlines will need to spend — and how much more in lost revenue they'll see — while they adapt to the new reality.The backdrop: Revenue and passenger loads have plummeted at an unprecedented rate for the U.S. airline industry, and no one knows what's ahead.Major airlines' share prices have been cut in half since the global pandemic started to roil the stock markets.One Wall Street analyst is withdrawing his price target for American Airlines altogether — a sign that the waters are so murky that taking a guess at where the stock could be by year-end isn't worth it."Even as Delta is burning more than $60 million in cash every day, we know we still haven’t seen the bottom," CEO Ed Bastian said last week.Yes, but: Even when the economy comes back to life and social distancing measures are relaxed, huge questions for airlines will remain.Will people fly at the rate they did before, particularly business travelers who have grown accustomed to holding meetings virtually? Will passengers be more skittish about packing together in tight rows of seats, and will carriers accommodate their concerns? It's "possible that a number of airlines will have gone bust and uneconomic discounts will be necessary to attract demand back,” Olivier Ponti, vice president at travel-industry data firm ForwardKeys, told Reuters.What to watch: Most of the major U.S. airlines — including American, Delta, United and JetBlue — submitted applications for federal aid on Friday, per CNBC.It's still unclear how much each company requested, or what terms they'll have to meet in order to receive the money. If any of the companies accept aid, the government has a right to take a stake in the businesses, but may opt for other forms of compensation. Treasury Secretary Steven Mnuchin gets the final say. The bottom line: Airlines are fighting for survival, and an uncertain environment awaits them on the other side of the pandemic."We are not expecting to re-start the same industry that we closed a few weeks ago ... the industry processes will need to adapt," Alexandre de Juniac, CEO of International Air Transport Association, a global airlines group, said Tuesday.