With regards to Hapag Lloyd Express, I am sure that the enter Boeing 737-700 & Fokker 100 fleet are wetleased from Germania Flug, so these aircraft and their crews would simply be deployed to another operation. Where this is not the case, I imagine that they will simply be reintergrated into Hapagfly.
Similar situation with Thomsonfly. The airline already uses Britannia's AOC, aircraft & office facilities, it makes sense to use the strong brand that has now been grown out of CVT/BOH/DSA areas in the no-frills market, to use this new name to cater for the growing dot commers travel market!