I'm afraid there is absolutely no evidence to show it
There have been more direct flights from LHR to the rest of the world than from Frankfurt for years and yet the Germans have persistently out sold UK industry world wide
FRA has more destinations than LHR.
CDG has more destinations than LHR.
AMS has more destinations than LHR.
That's only going to get worse if as you wish, we sit on our bums and allow LHR to stagnate further. That's no way to run a business.
Your idea that the way to beat the Germans is to allow the number of hub destinations to wither further has no logic.