Originally Posted by
jiejie
I wouldn't necessarily make that assumption.
At any rate, a traveller could backtrack and cross to Laos and then overland to Thailand from there. Or to Vietnam and fly. Or fly to a third country from REP if all flights to Thailand are toast. Point is, with Cambodia, there are plenty of Plan B, C, and D options.
Unless it was recently instituted there is no visa on arrival for Laos at the Mekong border. And getting into Vietnam would also require a visa issued ahead of time (unless things were bad and they were waiving this... unlikely). So, B and C are not great plans and would need to be addressed ahead of the actual need. Which relegates plan D.