I'm a bit nervous for the next album. I feel like it could make them or break them, especially in the US (they seem more powerful as a brand in the UK).
It should sell well regardless but their typical boyband fanbase should start declining and if they don't have one or several crossover hits then they might severly decline with the 5th album. On the other hand, if it has one or several successful singles among all demographics, then they could really start looking at a potential pop legends status.
