If they can snoop on encrypted traffic, then the systems for encryption will be changed until they cannot. There is no point in encryption if someone can snoop on it. It does not matter what the technology is, this is a simple fact.
If/when they cannot snoop on encrypted traffic then everyone using encryption for facebook, twitter, gmail, games, etc, etc, etc, will not be visible to them even to extract "communications data".
Please pass this message on to your MP. It is as non technical as I can make it. Thanks.