Imagine a future where your great great great grandchild is seeking refuge in a foreign country, instigated after the collapse of the UK. No legal routes out were available.
He/She is on a boat headed for the shore of said foreign country.
The boat is struggling under the weight.
Surely the country will assist, seeing those on board are in trouble.
Nope. They sit and watch. They do nothing.
Your grandchild thrice removed drowns.
They're dead.
I prefer to think that countries will rescue migrants if need be, however backed up by an extremely robust processing system.