Losing the overflights
Pretty much as it was about 20 years ago, isn't it?
Everybody managed back then.
Not as convenient or economical as overflight but not the end of the world either, for either of the party.
SIA flight to Houston through Moscow? Would that be affected?
CX might have to duck and weave a bit to get to London.
Aussie flights through the middle east? So what's different.
Asian carriers to east coast USA will need to dodge Kamchatka / Sakhalin, same as they did 20 years ago.
If they are affected at all.
Inconvenient and costly, most certainly.
Unmanageable? I don't think so.