Yes that article does make for worrying reading Wiggy.
On the revenue side it seems like 2 large customer bases for BA will show less tendency to travel due to Brexit. The first group are the city and business types. The current uncertainty puts corporate deals, IPOs etc on hold until there is some idea of what a future trade agreement will look like with the EU, thus there will be less demand for business travel. The other group to be affected will be UK based would-be holiday makers now less likely to travel due to the value of Sterling.
On the flip-side it is worth noting that a devalued sterling makes our flights, and our country, more affordable for foreign points of sale, and other BA markets such as connecting India-USA flows via LHR may be unaffected so it is not all bad news.
On the cost side the price of fuel (paid for in US dollars) has just shot up as a result of sterling's devaluation. There will also be significant other costs paid for in foreign currency that have now just shot up in price. But we do also earn revenues in foreign currency so this mitigates it to some extent.
Overall the analysts paint a bleak picture in the short to medium term. I wouldn't expect any immediate reaction from IAG ( apart from perhaps accelerated cost cutting and delaying capex). But if things do go south it isn't unthinkable for the company to shrink again with 744s being sent to the desert. On topic this could halt any further recruitment, apart from that required for new sickness assumptions, retirements, and EASA, although these would be far smaller numbers than required for growth.
Fingers crossed and all that.