It's still a very popular route for sailing. You essentially ride the tropical conveyors from the Azores until the Indian Ocean. The Americas are a minor inconvenience, solved by the Panama Canal.

It's getting back which is the issue - your have the disastrously weathered cape of good hope, or the pirate-infested Aden. It's quite ironic that if you want to sail around the world, it's the ancient routes that are the worst parts.

If Columbus had discovered the Americans were an archipelago, or if the gulf of mexico had properly separated north and south, the discovery would have been a very popular trade route - even today.

What if rising sea level puts Panama under water?

A bit out of my wheelhouse, but I tend to believe the drawbacks would outweigh the benefits.