WTTC prediction is not bullish, it's dreamtiming. Anticipating a 17% downfall compared to 2019 is ridiculous. Australia may have the virus under control (good job BTW) but even if Europe/USA are fully vaccinated by mid year, the net reduction in income is going to severely affect travel for years.
Some jobs are never going to return, online shopping/working has moved forward exponentially due to the pandemic so high street retail is going to shrink even further (and it wasn't in good shape before the pandemic).
That's just one example, think pubs, theatre, cinema, tourism, office real estate and you're scratching the surface.