The current thinking is that the trade value would be calculated by the new shortest distance. Historically speaking this would be similar to how salt used to be very expensive but is now very cheap as methods for production and transportation have improved.

Spoon - It would still be useful for a research because it makes them less reliant on the large storage capacities / travel speeds of the high end trading vessels. It also means a player can more readily keep planets connected that would otherwise be too far apart to be useful so a player could cherry pick the most resource rich sectors to settle from across the entire galaxy. (this is less of an issue if you have matter transmitters but they only move resources and not ships as well.)

Additionally it's worth mentioning that this would also increase your options for establishing optimal trade partners since there's nothing that says you have to place a jump gate right next to your trading partner's planet.