VAA must be more worried after using their slot value as collateral...
For those who confuse LHR being at capacity and not being able to grow so divert transfer pax and cargo to other airports, the constraint is on aircraft movements not passenger numbers.
Bigger aircraft can operate the existing slots to grow passenger numbers. But with yields starting to fall, I expect airlines to start turning on transfers to grow volume. Easier & quicker than shaking loose the local market.
That only works if you have a hub. Even 30% transfers makes thin routes viable. Get rid of that & the local market will have less destinations to choose from & pay higher fares.