I hope the the Thargoids are going to be a bit more interesting and complex than just the single minded shooty enemy most seem to be able to come up with.
I hope they will react strongly to provocation and even take systems they consider to be important, but it would make little sense to want to waste resources on conquering the entire human bubble with hundreds of thousands of planets that could be of little interest to them.
As this is not a single campaign game that ends after a few hours of gameplay, but an open ended spacesim in the Elite tradition that will have to be playable for many years to come and be of interest not just to those who want to do combat for ever, but also to those who want to trade or mine or explore etc, having the Thargoids "crush the bubble" would be a stupid thing to do.
Really? Even if, for example, the bubble was 'crushed' for a period (providing ample gameplay opportunities in the process) before significant rebuilding efforts got underway (providing ample gameplay opportunities in the process)?
I realise that will scare some players as a concept because it might provide then with gameplay that isn't essentially doing the same thing over and over again and I sense vast amounts of the fear of change in this thread.