Being an Eindhoven resident I'm afraid Eindhoven will "never" work from Gatwick.
We've got Ryanair 2x daily to Stansted to capture the leisure passengers that go to London. Every other airline is more expensive(generally speaking) so I think people will stick with Ryanair.
For the business people we have Cityjet to London City 2x daily.
So who is left to fly to Gatwick? Maybe a few people that need to go to Brighton but they will never be able to fill a plane with only those people. Besides they will just travel to Amsterdam and take easyJet there.
But I hope I will be wrong!