There's a very good chance that there will never be an effective vaccine for this virus. However, there is also a very good chance that the mortality rate is going to end up looking like seasonal flu (in the order of 0.1-.3%). Despite all the hysterical, media driven hype this remains a virus that overwhelmingly causes no or mild symptoms, except in statistically very limited cases.
In other words, we are going to learn to live with it. Leisure travel in particular is likely to rebound strongly, because people will want to go on holiday. Business travel is another story and I fear that it may be irreparably damaged.
With all of that said, I don't see there being any jobs for cadets within three years. Training now would be foolhardy, unless you have £10s of thousands that you can afford to lose.