I feel like there could be some far away distress sort of situation where Republic City would need to send police to help, which would be enough reason for Mako and Bolin to go. With Asami's company, I see her expanding and that could mean getting more bodies to help run it while they travel around a bit. I don't really see things staying in the city, kind of hard to sustain plots on a compact setting. LOK missed out on the extensive travel and side plots ALTA could have fun with. The team is still freaking young, there's no reason their jobs should hold them back so soon IMO.